304 pubblicazioni classificate nel seguente modo:

Modeling coastal inundation for adaptation to climate change at local scale: the case of Marche Region (central Italy)
FRONTIERS IN CLIMATE
Autore/i: Baldoni, Agnese; Melito, Lorenzo; Marini, Francesco; Galassi, Gaia; Giacomin, Patrizia; Filomena, Giorgio; Barbizzi, Natalino; Lorenzoni, Carlo; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Climate change is raising sea level rise and storminess effects on coastal systems, affecting the morphology of coastlines and impacting coastal communities and ecosystems. It is essential to gain information at an adequate scale to identify effective adaptation measures. This is of major importance in areas combining high vulnerability to climate change with high socio-economic development, like the Northern Adriatic coastal area. To this aim, in this work two different approaches have been applied to investigate inland penetration of sea water along the Marche Region: (a) a simple "bathtub" method applied to the entire Marche coastline, to highlight areas likely prone to intense inundation; (b) a more accurate numerical model applied to two test sites, to gain detailed knowledge of inundation perimeters. Both approaches have been applied with forcing conditions provided by the Intergovernmental Panel on Climate Change and the Copernicus Climate Change Service through the RCP8.5 emission scenario projected to 2070. Results showed that a 100-year return period sea storm would cause the inundation of beaches and infrastructures located along the coast, as well as affecting harbor facilities and urban areas. Information obtained with the model has been integrated in the Regional Plan for Adaptation to climate change to define specific adaptation measures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/327071

Test Reference Year for wave energy studies: Generation and validation
RENEWABLE ENERGY
Autore/i: Memmola, Francesco; Contestabile, Pasquale; Falco, Pierpaolo; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: In a perspective of impoverishment of the fossil fuel and preservation of the natural environment, the sea wave energy is being increasingly regarded as alternative and promising resource. A key aspect to take in consideration for the deployment of Wave Energy Converters is the local characterization of the wave climate. In this contribute, a methodology for the calculation and validation of a site-specific Test Reference Year (TRY), from a multiyear dataset such ERA-Interim and ERA-5, to be used in wave energy conversion studies is proposed. Comparison of the two datasets with observed data gives ERA-5 as the best dataset. The methodology applied for the TRY generation has proven to be very effective, with the daily sum of Hs and Tm being the most effective indices for the TRY generation and in general Hs about twice more important than Tm. Once obtained, the TRY is applied in order to force an implementation of the Simulating WAves Nearshore (SWAN) model in an area of the central Adriatic Sea to characterize the area.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/328731

Cardiac and vascular modeling in sport
The Bioengineering of sport
Autore/i: Zitti, Gianluca; Mousavi, SEYYED MAHMOUD; Brocchini, Maurizio; Pedrizzetti, Gianni
Editore: Pàtron editore
Luogo di pubblicazione: Bologna
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325294

Harbour Hydro-Morphodynamics and Freshwater Discharges: The La Spezia Arsenale Case
Water
Autore/i: Colangeli, C.; Baldoni, A.; Melito, L.; Corvaro, S.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325156

A storm driven turbidity maximum in a microtidal estuary
ESTUARINE, COASTAL AND SHELF SCIENCE
Autore/i: Postacchini, M.; Manning, A. J.; Calantoni, J.; Smith, J. P.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: Many macro- and mesotidal estuaries are characterized by Turbidity Maxima Zones (TMZs), regions with suspended solid concentrations that are much higher than those found throughout the rest of the estuary. Such regions are located near the upriver limit of salt intrusion and their position and extent are modulated and driven by tidal oscillations, especially in estuaries where tidal forcing is large. Hence, pronounced TMZs are not typically expected in micro-tidal estuaries. Field experiments were carried out in the microtidal estuary of the Misa River (northeast coast of Italy) with the aim to analyze riverine-coastal ocean interactions during different climatic conditions, freshwater discharge and tidal forcing. The goal was also that of identifying factors and episodic conditions that could lead to the evolution of ephemeral TMZs in this microtidal estuarine system. Observational results, combined to a flocculation model suite, describe the hydrodynamics, morphological bed evolution, water chemistry and floc dynamics within the estuary during wintertime quiescent and stormy periods. Pronounced TMZs with different location and extent were observed during two storms with different intensities, when enhanced freshwater discharge, wave action and tidal oscillation generated significant stratification of the lower estuarine water column. Higher turbidity values were observed throughout the TMZ during the smaller/weaker storm, while stronger surface mixing during the stronger storm led to greater dispersion of the (re-)suspended particulate load throughout the upper water column, providing a less pronounced TMZ along the bed of the lower estuary. Observations in the Misa River, potentially valid for other microtidal estuaries, show that: 1) episodic storm conditions that significantly increase freshwater discharge can lead to the evolution of an ephemeral TMZ that is modulated, but not controlled, by tidal oscillations and surface mixing conditions; 2) ephemeral TMZ localization, intensity, and extent during episodic storm events is a function of storm intensity; 3) moderately enhanced freshwater flow during an episodic storm event promotes a high degree of stratification, allowing for the formation of large flocs with great settling rates, leading to a pronounced TMZ forming downriver of the landward limit of seawater intrusion; whereas higher freshwater flows during stronger storm events lead to less stratification, greater bottom turbulence and potential TMZ suppression near the riverbed, with shear conditions promoting smaller flocs with lower settling and a greater potential for suspended particulate export from the lower estuary to coastal waters.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/319812

Steady streaming under a surface wave propagating over a rough bottom: A model of the bottom boundary layer
PHYSICS OF FLUIDS
Autore/i: Vittori, Giovanna; Blondeaux, Paolo; Brocchini, Maurizio; Melito, Lorenzo; Postacchini, Matteo
Classificazione: 1 Contributo su Rivista
Abstract: The steady streaming generated by nonlinear effects at the bottom of a propagating surface wave is determined when the bottom is characterized by a roughness, the size of which scales with the boundary layer thickness. Therefore, the cornerstone contribution by Longuet-Higgins, who considered a smooth bottom, is extended to sea waves and sandy bottoms characterized by a grain size that ranges from fine silt to fine gravel. For values of the grain size d* up to 0.05 delta* , delta* being the thickness of the viscous bottom boundary layer, the velocity profile is practically coincident with that predicted by Longuet-Higgins. If the grain size is further increased, the steady velocity component becomes larger and reaches a maximum value that is approximately 70% larger than that predicted by Longuet-Higgins. The maximum of the steady velocity component is attained for d* = 0.6 delta*. A further increase in d* leads to a decrease in the steady velocity component that, however, keeps always larger than that predicted for a smooth bottom. As the roughness size increases up to the values typical of medium sand, the steady velocity component increases. Then, a further increase in the roughness size leads to a decrease in the steady streaming even though, in the range of the roughness size presently investigated, the steady velocity component is always larger than that predicted for a smooth bottom.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325155

From Boussinesq-Type to Quasi-3D Models: A Comparative Analysis
JOURNAL OF HYDRAULIC ENGINEERING
Autore/i: Melito, Lorenzo; Antuono, Matteo; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: By comparing model results from tests of steady and oscillatory flows over a submerged bar (of interest for both riverine and marine environments), we highlight similarities and differences between a state-of-the-art Boussinesq model and a recently developed non-hydrostatic, quasi-three-dimensional (3D) model. To make the comparison as clean as possible, the complexities due to breaking-induced turbulence are avoided by suitably tuning the flow strength. Although the main flow features are similarly described by the two models, the non-hydrostatic model predicts the occurrence of extra, small-scale stationary oscillations on top of a submerged obstacle in the case of a steady current. This is attributed to a pattern of alternating upward and downward vertical velocity over the sill top, presumably due to rapidly converging flows as they climb over the submerged obstacle. The non-hydrostatic model overall allows for a more complete representation of flow dynamics in the vertical direction, with respect to the Boussinesq-type solver. This becomes necessary when tackling fundamental and applicative problems characterized by intense vertical flows (e.g., interactions of fluids with structures).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/316513

Particle dynamics due to interaction between a breaking-induced vortex and a nearbed vortex
PHYSICS OF FLUIDS
Autore/i: Brocchini, Maurizio; Marini, Francesco; Falchi, Massimo; Postacchini, Matteo; Zitti, Gianluca
Classificazione: 1 Contributo su Rivista
Abstract: A single regular wave, travelling over a submerged abrupt discontinuity, is able to generate a pair of counter-rotating vortices. A nearbed vortex is generated by the flow separation that occurs at the bed, while a surface vortex can be generated by either a direct (co-rotating vortex) or a backward (counter-rotating vortex) breaking. Starting from recent laboratory test results, which showed the influence of the wave nonlinearity on the interaction between the counter-rotating vortices and led to the identification of three different regimes, the present work illustrates the main findings obtained from the optical analysis of the flow field induced by three waves, each belonging to a specific nonlinear regime. Specifically, for each test, synthetic particles have been seeded within the domain, with the aim to obtain long-lasting trajectories driven by the Eulerian flow field obtained through the Particle Tracking Velocimetry (PTV) analysis, to be studied by means of single-particle and multi-particle statistics. Both absolute and relative statistics confirm that a ballistic regime exist just after the particle release at each location of the domain. At larger times, the absolute statistics suggest a subdiffusive regime both within the vortices and between such areas (in correspondence of the breaking-induced jet), followed by a superdiffusive regime, dominated by rotation and particle release. Differently, the relative diffusivity suggests the occurrence of a superdiffusive regime at t>TL, corresponding to enstrophy cascade and exponential growth, followed by a Richardson regime and then by an oscillatory behavior, during which particles are periodically trapped and released by vortices.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/309956

Dynamics of a pile-moored fish cages in current and waves: A numerical study
OCEAN ENGINEERING
Autore/i: Zitti, G.; Novelli, N.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: We propose a numerical study of the dynamics of a double-constrained cylindrical pile-moored fish-farm cage, to be possibly installed at the foundations of dismissed offshore structures. Our model, derived from the net-truss model of Kristiansen and Faltinsen (2012), takes into account the elasticity of the net material, the real size of the net and is applied with and without mesh-grouping approaches, this allowing us to evaluate the range of validity of mesh-grouping techniques. First, cage dynamics have been studied with small-scale tests, in which the numerical model accurately reproduces the behaviour of the cage in both sea currents (velocity in the range 0.5−1m/s) and waves of small amplitude (with height of 1 m and period in the range 4−32 s). Use of the net real size for the computation grid of small-scale tests allows for identification of the main phenomena influencing the load distribution and the volume loss, which are: the dominant sail-shape deformation in the streamwise direction, the flattened deformations in the cross flow direction, and high-frequency oscillations in the vertical direction in long waves. Subsequently, a prototype-scale test is run to simulate the dynamics of a realistic installation of a double-constrained cylindrical pile-moored fish-farm cage in the Adriatic sea (considering both 1m/s sea current and storm sea state characterized by a peak period Tp=4 s and significant wave height Hs=1.5 m), showing that the major loads are a compression load on the pile up to 1 kN and a bending moment at the pile base up to 9.1 kNm. The proposed configuration always showed a small net relative volume loss VL<5%.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/309955

Upriver Propagation of Tidal Waves and Mouth Bar Influence at a Microtidal Estuary: Observations and Modeling
Proceedings of the 39th IAHR World Congress
Autore/i: Postacchini, Matteo; Darvini, Giovanna; Perugini, Eleonora; Martinelli, Jacopo; Ilari, Marco; Brocchini, Maurizio
Editore: International association of hydro-environment engineering and research
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The estuary of the Misa River, located in Senigallia (central Italy), is a micro-tidal environment typical of the Adriatic basin. The present work focuses on the numerical modeling of the tidal action along the final stretch of the river, also in relation to the role of local river bedforms, and builds on field data obtained from: two hydrometers recording the river stage, an acoustic sensor H-ADCP collecting river stage and discharge during flood conditions, a tide gauge measuring the water-surface level in the sea, a suite of instrumentation deployed during a field campaign in 2014. The river topography and bathymetry are modeled using a digital terrain model, surveys of the estuarine area, surveys of specific cross-sections in the river. After the model calibration, which provides the optimal choice of the riverbed roughness, the work analyzes the role of the tide forcing, which propagates upstream for almost 2 km. The effects on the hydrodynamics induced by bedforms located at the estuary are also investigated. Specifically, a partially emerged bar, generated in the recent years upstream of the river mouth, intermittently shows up and moves within the estuary. Such bedform significantly affects the local dynamics and produces relevant changes in the final reach of the river, reaching distances of more than 1 km from the mouth.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/314508

Numerical evaluation of the action on a pile-moored fish cage forced by a storm sea state in different configurations
Proceedings of the 39th IAHR World Congress
Autore/i: Zitti, Gianluca; Novelli, Nico; Brocchini, Maurizio
Editore: International association of hydro-environment engineering and research
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The conservation and reuse of the foundation of offshore platforms, at times, can be more ecologically sustainable than their complete removal, which can result in the loss of biodiversity. In our work we consider fish-farming as possible reuse of offshore depleted oil and gas mono-pile infrastructures, being the role of aquaculture in fish-food supply continuously increasing in the last decades. Offshore fish-farm cages are exposed to strong actions and knowing the dynamical response of the cage to different marine forcing is fundamental for the design of the structure. Hence, the dynamics of cylindrical pile-moored fish cages has been studied numerically with a net-truss model, including the screen model for the viscous forces proposed by Kristiansen and Faltinsen (2012) and the elasticity of the net trusses (Zitti et al.,2020, 2022). The model simulates a cylindrical cage fixed to a top ring and a bottom ring, which are moored to the central tubular pillar, whose net is characterized by solidity ratio Sn=0.087, material density pnet=1140 kg/m3, and Young modulus E =81Ί06 N/m2. The grouping method with G=10 is included in the model, for the reduction of the computational cost of the simulations. The cage net is forced with a flow derived by a linear superposition of the flows associated to linear waves, based on a JONSWAP spectrum representative a storm sea state typical of the Adriatic sea, on the Italian East coast, where a number of mono-pile oil and gas infrastructures are located. Different configurations of the cage are simulated and the resulting actions on the support system are compared.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/308027

A Semi‐Empirical Approach for Tsunami Inundation: An Application to the Coasts of South Italy
GEOPHYSICAL RESEARCH LETTERS
Autore/i: Melito, Lorenzo; Lalli, Francesco; Postacchini, Matteo; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Tsunamis in the Mediterranean Sea have been increasingly investigated recently due to past destructive events. We present a novel operational approach for evaluating tsunami-induced inundation, based on a generalization of Green's law and a chain of intermediate and small-scale simulations. At the intermediate level, simulations with a linear solver are made to identify the distribution of a novel parameter, namely α, condensing all nearshore wave transformations other than shoaling. α represents a proxy for coastal susceptibility to the tsunami impact. Small-scale modeling of coastal flooding performed at locations for which a DTM is freely available, at the Esaro river estuary (Calabria) and in Bari (Apulia), yields inundation levels that compare well with those obtained via intermediate-scale modeling, with a saving in computational time of about 41%. This demonstrates the value of α to “scale” the offshore wave input and reduce computational effort to evaluate flooding at regional scale.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/303193

Sea level perturbations caused by Bora in the northern Adriatic
NATURAL HAZARDS
Autore/i: Qayyum, R.; Melito, L.; Calantoni, J.; Brocchini, M.; Sheremet, A.
Classificazione: 1 Contributo su Rivista
Abstract: The Jan. 2014 Bora storm had a measurable impact in the northern Adriatic. At Senigallia, in the wake of the storm, the EsCoSed field experiment (Brocchini et al. in Geology 385:27–40, 2017) recorded 5-cm sea-level fluctuations with a characteristic period of 100 min, exhibiting a distinctive, discrete frequency spectrum. Sea level oscillations of similar height and time periods were also recorded by tidal gauge at Venice. Given the sensitivity of Venice flooding to sea-level perturbations and the localized, basin-transversal jet structure of the Bora winds, the observations are both significant and surprising. We hypothesize that the oscillations were caused by wind setup generated by the Bora jets, and investigate the event using a simplified, linear mathematical model. Model simulations support the wind setup hypothesis and suggest that the oscillations observed were a mixture of edge-waves and two-dimensional seiches with a significant basin-transversal component. The spatial structure of seiches explains the basin-longitudinal reach of Bora storm. A comparison with the analysis of Venice historical records of extreme sea level events, compiled by Ferrarin et al. (Sci Rep 12(1):1–11, 2022), shows that Bora-induced oscillations are of the same order of magnitude as general seiche constituents. Their contribution, however is, much less understood. Further work is needed to evaluate the flooding threat posed by Bora storms.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/305359

A new process-based, wave-resolving, 2DH circulation model for the evolution of natural sand bars: The role of nearbed dynamics and suspended sediment transport
COASTAL ENGINEERING
Autore/i: Pourzangbar, A.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: We study the migration of natural sand bars that evolve in the nearshore by means of a new process-based waveresolving, 2DH circulation model. In order to perform reliable and accurate computations, the robust Nonlinear Shallow Water Equations (NSWEs) hydro-morphodynamic solver of Brocchini et al. (2001) and Postacchini et al. (2012) implements a detailed description of the Bottom Boundary Layer (BBL) dynamics and a new predictor for the Suspended Sediment Transport (SST) based on the solution of a Depth-Averaged Advection-Diffusion Equation (DAADE) for the sediment concentration. The robustness and accuracy of the enhanced model are validated against literature theoretical, experimental, and numerical results, all comparisons highlighting good performances and clarifying the role of both BBL and SST contributions, the former one having a larger positive influence than the latter one on the results. Both original and enhanced models are, then, used to predict the evolution of the sand bar system that characterizes the nearshore of Senigallia (AN). The analysis leverages the field observations collected at such a site by means of the Sena Gallica Speculator video-monitoring system. Modeling of the storm-forced sand bar migration patterns reveals that: 1) the enhanced model can adequately reproduce the seaward migration of the sand bars of the system; 2) the process of shoreline retreat in coincidence with the generation of a new-born bar is well described; 3) inclusion of the BBL improves quantitative prediction of the bar crest migration; 4) the SST, beyond improving the prediction of the bar crest location, induces some smoothing of the bar profile, in line with the literature findings of SST being a stabilizing factor for the bar emergence.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/314006

Improving the Performances of a Novel RANS Model for Breaking Water Waves Using a Subgrid Approach and Non-equidistant Layers
WATER WAVES
Autore/i: Iravani, N.; Badiei, P.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/319831

Interaction between breaking-induced vortices and near-bed structures. Part 1. Experimental and theoretical investigation
JOURNAL OF FLUID MECHANICS
Autore/i: Brocchini, M.; Marini, F.; Postacchini, M.; Zitti, G.; Falchi, M.; Xie, Z.
Classificazione: 1 Contributo su Rivista
Abstract: The present work describes the vortex-vortex interactions observed during laboratory experiments, where a single regular water wave is allowed to travel over a discontinuous rigid bed promoting the generation of both near-bed and surface vortices. While near-bed vortices are generated by the flow separation occurring at the bed discontinuity, surface vortices are induced by the wave breaking in conjunction with a breaking-induced jet. A 'backward breaking' (previously observed in the case of solitary waves) occurs at the air-water interface downstream of the discontinuity and generates a surface anticlockwise vortex that interacts with the near-bed clockwise vortex. With the vortex-vortex interaction influenced by many physical mechanisms, a point-vortex model, by which vortices evolve under both self-advection (in relation to both free surface and seabed) and mutual interaction, has been implemented to separately investigate the vortex- and wave-induced dynamics. The available data indicate that both self-advection and mutual interaction are the governing mechanisms for the downward motion of the surface vortex, with the effect of the breaking-induced jet being negligible. The same two mechanisms, combined with the mean flow, are responsible for the almost horizontal and oscillating path of the near-bed vortex. The investigation of the vortex paths allow us to group the performed tests into three distinct classes, each characterized by a specific range of wave nonlinearity. The time evolution of the main variables characterizing the vortices (e.g. circulation, kinetic energy, enstrophy, radius) and their maximum values increase with the wave nonlinearity, such dependences being described by synthetic best-fit formulas.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/302022

Numerical simulation of coronary arteries blood flow: effects of the aortic valve and boundary conditions
Theoretical and Applied Mechanics - AIMETA 2022
Autore/i: Mousavi, S. M.; Zitti, G.; Pozzi, M.; Brocchini, M.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/313928

MONstEr: A Deep Learning-Based System for the Automatic Generation of Gaming Assets
Lecture Notes in Computer Science
Autore/i: Brocchini, M.; Mameli, M.; Balloni, E.; Sciucca, L. D.; Rossi, L.; Paolanti, M.; Frontoni, E.; Zingaretti, P.
Editore: SPRINGER INTERNATIONAL PUBLISHING AG
Luogo di pubblicazione: GEWERBESTRASSE 11, CHAM, CH-6330, SWITZERLAND
Classificazione: 2 Contributo in Volume
Abstract: In recent years, we have witnessed the spread of computer graphics techniques, used as a background map for movies and video games. Nevertheless, when creating 3D models with conventional computer graphics software, it is necessary for the user to manually change the placement and size. This requires expertise of computer graphics architecture and operations, which is time demanding. Applying Artificial Intelligence (AI) to games is currently an established research field. Starting from such premises, in this paper MONstEr (dEEp lEArNiNG GENErAtiON AssEt) a system for the automatic generation of virtual asset for videogames is presented. MONstEr exploits the principle of Deep Learning (DL) and in particular Generative models to automatically design new assets for videogames. The DL pipeline is the core of this system and it is based on a Deep Convolutional Generative Adversarial Network followed by Pixel2Mesh architecture for the 3D models generation. The approach was applied and tested on a newly collected dataset of images, "GameAssetDataset" which comprises characters representation extracted thanks a web crawler algorithm specifically developed for its acquisition. MONstEr expedites the implementation of solutions for new gamining environments, requiring only a small intervention in the 3D construction to insert the object in the game scene.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/315913

Wave- and Tide-Induced Infragravity Dynamics at an Intermediate-To-Dissipative Microtidal Beach
JOURNAL OF GEOPHYSICAL RESEARCH. OCEANS
Autore/i: Melito, Lorenzo; Parlagreco, Luca; Devoti, Saverio; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Numerical simulations of a range of wave climates and tide conditions made with the model XBeach are exploited to study propagation, evolution, dissipation, and reflection patterns of infragravity waves (IGW) at the intermediate-to-dissipative beach of Sabaudia (Tyrrhenian sea, Italy). On the basis of a novel calibration process performed using field swash properties collected by a nearby monitoring station, the model reproduces average run-up characteristics with good skill (Willmott index of agreement of 0.61 for R2%). IGW at Sabaudia beach evolves exclusively as bound long waves growing across the shoaling region for both mild and intense wave climates. Furthermore, values of the dimensionless bed slope βH at which transition from steep-to mild-slope behavior occurs are higher than the threshold commonly assumed in the literature. Finally, although the small tide (0.4 m between mean high water spring and mean high water spring; tide range/breaking wave amplitude ratios between 0.14 and 1.1) does not alter bulk IGW reflection significantly, low tide is effective in reducing onshore IGW fluxes and, ultimately, reflection coefficients R2 selectively for intermediate IG frequencies. Our study, for the first time, gives clear evidence that the tide has a role in determining frequency-dependent IGW dynamics and altering the dissipative state of a mild sloping beach also in a microtidal environment.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/298404

Filling flows by wave impacts on walls: Laboratory and numerical experiments
PHYSICS OF FLUIDS
Autore/i: De Finis, S.; Lugni, C.; Bellotti, G.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: The phenomenon of filling flow, which may take place inside the fissures or cavities of maritime structures, due to the action of waves, has been studied mostly from an analytical point of view. The aim of this paper was to investigate such a process through an experimental approach, using both physical and numerical models. The most important filling flow properties were evaluated under different wave conditions (expressed in terms of acceleration and angular frequency). Numerical and physical results were compared with each other and with the analytical formulations proposed in literature. Good agreement was found between the experimental and the analytical results, especially for the velocity of the backflow jet and for the pressure inside the cavity. Finally, an empirical formula for the prediction of the pressures induced by the filling flow, related to the wave and the cavity geometry features, was proposed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/314009

A comprehensive study of the river plume in a microtidal setting
ESTUARINE, COASTAL AND SHELF SCIENCE
Autore/i: Baldoni, A.; Perugini, E.; Penna, P.; Parlagreco, L.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: On the basis of observations and modelling of the plume generated by the Misa River (AN, Italy), we performed a comprehensive study, which integrated different sources of information (field data, numerical simulations, etc.), of the generation and transport mechanisms of river plumes flowing into microtidal environments. First, we analysed images simultaneously acquired by both two shore-based stations and satellite to determine plume fronts and extensions. Then, we correlated such information with the estuarine forcing to recognize the plume generation and transport mechanisms. Being real-life events influenced by a combination of factors, we run numerical simulations to separately study each force and its influence on the plume evolution. We also performed simulations of two real-life cases, to compare the modelled and observed results. We identified the river discharge and the wind as the main generation and transport mechanisms, respectively. Moreover, waves could stir, suspend, and drag plume sediments, even if results showed that a river discharge associated with a return period smaller than 1 year produced a plume denser than 5-year return period waves. The transport mechanisms were responsible for the alongshore extension of the plume. The tide, even if secondarily, affected the plume evolution, depending on its phase shift to the river discharge peak. Particle Tracking Velocimetry from videos acquired by a shore-based station provided the surface velocity field in the final river stretch. This and the contributions by wind and waves were correlated with the plume extension through a power law.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/314007

A wave-breaking model for the depth-semi-averaged equations
JOURNAL OF FLUID MECHANICS
Autore/i: Antuono, M.; Lucarelli, A.; Bardazzi, A.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: We propose an efficient model for the description of the three-dimensional (3-D) evolution of breaking water waves in the nearshore region. A fundamental property of the model is its intrinsic ability to account for the 3-D dynamics of vorticity and the energy dissipation induced by wave breaking. In particular, the vorticity evolution is achieved through the use of mollified operators, an approach similar in spirit to that adopted in smoothed particle hydrodynamics. Further, since the model is based on depth-semi-averaged equations with a core structure similar to that of nonlinear shallow-water equations, it takes advantage of well-known numerical methods for hyperbolic equations, while permitting computation of local flows. Finally, the model relies on a limited number of tunable parameters and a very simple breaking criterion. All the above aspects allow for a simple and reliable representation of the main features of wave breaking at the time and spatial scales typical of the nearshore wave dynamics. A number of benchmarks are used to explore the properties of the model, which is tuned only once for all cases. Wave height decay rates are well described for both sloshing (thin) and shoaling (thick) spillers, and a good description is also provided of the vorticity field. A final run of an impulsive wave over a submerged breakwater is used to illustrate the representation of the 3-D vorticity dynamics.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/314008

Interaction between wave breaking-induced vortices and nearbed structures: preliminary numerical results and laboratory-test design
Atti del 37° Convegno Nazionale di Idraulica e Costruzioni Idrauliche. Ingegneria delle acque: cambiamenti globali e sostenibilità.
Autore/i: Brocchini, M.; Marini, F.; Postacchini, M.; Zitti, G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/299200

Wave-Forced Dynamics at Microtidal River Mouths
River Deltas - Recent Advances
Autore/i: Brocchini, Maurizio; Postacchini, Matteo; Melito, Lorenzo; Perugini, Eleonora; Manning, Andrew J.; Smith, Joseph P.; Calantoni, Joseph
Editore: IntechOpen
Classificazione: 2 Contributo in Volume
Abstract: Microtidal river mouths are dynamic environments that evolve as a consequence of many forcing actions. Under the hydrodynamic viewpoint, river currents, sea waves and tides strongly interact, and their interplay determines specific sediment transport and morphological patterns. Beyond literature evidence, information comes from field observations made at the Misa River study site, a microtidal river along the Adriatic Sea (Italy), object of a long-going monitoring. The river runs for 48 km in a watershed of 383 km2, providing a discharge of about 400 m3/s for return periods of 100 years. The overall hydrodynamics, sediment transport and morphological evolution at the estuary are analyzed with particular attention to specific issues like: the generation of vortical flows at the river mouth, the influence of various wave modes (infragravity to tidal) propagating upriver, the role of sediment flocculation, the generation and evolution of bed features (river-mouth bars and longitudinal nearshore bars). Numerical simulations are also used to clarify specific mechanisms of interest.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/291760

Initial investigation of athletes’ electrocardiograms acquired by wearable sensors during the pre-exercise phase
THE OPEN BIOMEDICAL ENGINEERING JOURNAL
Autore/i: Romagnoli, S.; Sbrollini, A.; Colaneri, M.; Marcantoni, I.; Morettini, M.; Zitti, G.; Brocchini, M.; Pozzi, M.; Burattini, L.
Classificazione: 1 Contributo su Rivista
Abstract: Aim: The aim of this study is to support large-scale prevention programs fighting sport-related sudden cardiac death by providing a set of electrocardiographic features representing a starting point in the development of normal reference values for the pre-exercise phase. Background: In people with underlying, often unknown, cardiovascular abnormalities, increased cardiovascular load during exercise can trigger sport-related sudden cardiac death. Prevention remains the only weapon to contrast sport-related sudden cardiac death. So far, no reference values have been proposed for electrocardiograms of athletes acquired with wearable sensors in the pre-exercise phase, consisting of the few minutes immediately before the beginning of the training session. Objective: To perform an initial investigation of athletes’ electrocardiograms acquired by wearable sensors during the pre-exercise phase. Methods: The analyzed electrocardiograms, acquired through BioHarness 3.0 by Zephyr, belong to 51 athletes (Sport Database and Cycling Database of the Cardiovascular Bioengineering Lab of the Università Politecnica delle Marche, Italy). Preliminary values consist of interquartile ranges of six electrocardiographic features which are heart rate, heart-rate variability, QRS duration, ST level, QT interval, and corrected QT interval. Results: For athletes 35 years old or younger, preliminary values were [72;91]bpm, [26;47]ms, [85;104]ms, [-0.08;0.08]mm, [326;364]ms and [378;422]ms, respectively. For athletes older than 35 years old, preliminary values were [71;94]bpm, [16;65]ms, [85;100]ms, [-0.11;0.07]mm, [330;368]ms and [394;414]ms, respectively. Conclusion: Availability of preliminary reference values could help identify those athletes who, due to electrocardiographic features out of normal ranges, are more likely to develop cardiac complications that may lead to sport-related sudden cardiac death.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/291630

Preliminary results on the dynamics of a pile-moored fish cage with elastic net in currents and waves
JOURNAL OF MARINE SCIENCE AND ENGINEERING
Autore/i: Zitti, G.; Novelli, N.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: Over the last decades, the aquaculture sector increased significantly and constantly, mov-ing fish-farm plants further from the coast, and exposing them to increasingly high forces due to currents and waves. The performances of cages in currents and waves have been widely studied in literature, by means of laboratory experiments and numerical models, but virtually all the research is focused on the global performances of the system, i.e., on the maximum displacement, the volume reduction or the mooring tension. In this work we propose a numerical model, derived from the net-truss model of Kristiansen and Faltinsen (2012), to study the dynamics of fish farm cages in current and waves. In this model the net is modeled with straight trusses connecting nodes, where the mass of the net is concentrated at the nodes. The deformation of the net is evaluated solving the equation of motion of the nodes, subjected to gravity, buoyancy, lift, and drag forces. With respect to the original model, the elasticity of the net is included. In this work the real size of the net is used for the computation mesh grid, this allowing the numerical model to reproduce the exact dynamics of the cage. The numerical model is used to simulate a cage with fixed rings, based on the concept of mooring the cage to the foundation of no longer functioning offshore structures. The defor-mations of the system subjected to currents and waves are studied.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287981

Effects of stiffness and configuration of brace-viscous damper systems on the response mitigation of offshore jacket platforms
APPLIED OCEAN RESEARCH
Autore/i: Vaezi, M.; Pourzangbar, A.; Fadavi, M.; Mousavi, S. M.; Sabbahfar, P.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: We investigate the effects of a brace-viscous damper system on the dynamic response of offshore platforms. To do this, offshore jacket platforms with various distributions and three different configurations of brace-viscous damper systems - toggle, chevron, and diagonal configurations - and a wide range of brace stiffness are numerically modelled under the loading of irregular waves in ANSYS software. The dynamic response of the developed numerical model and its various brace-viscous damper configurations are validated against literature experimental and numerical results. Such a validation revealed an excellent agreement between the numerical results and the benchmark data. The results suggest that the standard deviation of the platform displacement given by a toggle configuration is less than that due to the chevron and diagonal configurations. Moreover, the maximum reduction of the base shear force is achieved by the application of the toggle configuration. Regarding the brace stiffness (area), for a reference damping coefficient of 500 N.m/s, a 54% increase in the brace area (from 42 to 91.8 mm2) results in a 21.26%, 38.61%, and 17.57% reduction in the structure displacement response for the diagonal, chevron, and toggle configurations, respectively. Using the results of the numerical simulations, we propose the spatially-optimized distribution of the brace-viscous damper system. Comparing the numerical results of this paper with those of field observations it was shown that the viscous damper with toggle configuration outperforms both the viscoelastic damper and uncontrolled platforms in terms of dynamic response.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287980

Long-term evolution of an inner bar at the mouth of a microtidal river
ESTUARINE, COASTAL AND SHELF SCIENCE
Autore/i: Baldoni, A.; Perugini, E.; Soldini, L.; Calantoni, J.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: We conducted, for the first time, a study of the long-term evolution of an inner mouth bar in a microtidal environment that complements field observations with detailed numerical modelling of the same morphodynamics. Images collected by a video-monitoring station, from 2016 to 2019, were processed to study the evolution of a persistent inner mouth bar formed inside the highly engineered Misa River estuary (Senigallia, Italy) after years of reduced precipitation and discharges. We developed a semi-automatic procedure to detect the emerged area of this deposit. We seek to quantify the relationship between the long-term evolution of the bar and the forcing from the river, waves and tides. The observed high peaks in river discharge caused a strong downriver bar migration (i.e. almost twice the river width). Conversely, the observed sea storms produced an upriver bar migration smaller than one river width. A much slower and weaker (less than half the river width) upriver migration was also observed during periods of large area accretion and due to mild wave climate. Moreover, results showed that the sea water level variation did not directly impact the morphodynamics of the estuary, affecting the emerged portion of the bar only. Numerical simulations, run with Delft3D, were used to complete the information coming from field observations. After some checks on the proper use of the solver for the scenarios and environments of interest, some parametric simulations were run to highlight the role of the different forcing on the bed evolution. Simulations showed, as expected, erosion of the riverbed and significant downriver migrations (four river widths) during peaks of river discharge comparable to the 1-year return period discharges. Numerical results also showed upriver sediment transport when the wave forcing was dominant, with 10-years return period waves inducing an upriver bar migration in the order of one river width. Then, one real-life event was simulated to inspect the interaction of the various forcing and to compare their effects with the observations. Our analysis provides new insight into the complex morphodynamics in a microtidal estuary when weak river discharge is opposed by sea waves driving upriver sediment transport. A more thorough understanding of the morphodynamics is needed for future forecasting of the formation and evolution of sediment deposits inside estuarine channels that can inhibit both navigation and the flux of sediment from the river to the estuary.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/298934

Upstream Propagating Long‐Wave Modes at a Microtidal River Mouth
e-proceedings of the 4 th EWaS International Conference Valuing the Water, Carbon, Ecological Footprints of Human Activities
Autore/i: Postacchini, Matteo; Melito, Lorenzo; Sheremet, Alex; Calantoni, Joseph; Darvini, Giovanna; Corvaro, Sara; Memmola, Francesco; Penna, Pierluigi; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/290536

Novel free surface boundary conditions for spilling breaking waves
COASTAL ENGINEERING
Autore/i: Iravani, N.; Badiei, P.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: The breaking of gravity water waves induces both strong turbulence near the free surface and air–water mixing, which are not captured in currently-available single-phase, non-hydrostatic Reynolds Averaged Navier Stokes (RANS) models. In order to account for such dynamics, the boundary conditions proposed by Brocchini (2002) have been implemented in a two-dimensional vertical (2DV) non-hydrostatic RANS numerical model. For the theoretical boundary conditions of Brocchini (2002) to be applicable in the numerical model, appropriate closures have been adopted and mathematical equations have been proposed to calculate the coefficients introduced in the mentioned boundary conditions. Navier Stokes equations along with different turbulence closure models have been solved using finite volume method and pressure correction technique. According to the new boundary conditions, the normal-to-mean surface gradient of the turbulent kinetic energy (TKE) differs from zero and is computed as a balance between production and dissipation of TKE within the air–water mixing layer. Also, the kinematic and dynamic boundary conditions have been modified accordingly, to account for the effects of the thin two-phase layer formed at the free surface. The modified kinematic boundary condition allows for the mass exchange between the two-phase layer and the main body of the water. For the first time it is demonstrated that the proposed simple analytical model of Brocchini (2002) leads to improvements in the prediction of incipient breaking and the wave characteristics in the surf zone. This opens the way to a new, accurate but numerically low cost, approach for the computation of the air–water mixing that characterizes breaking waves. All the many benchmarking tests run to verify the ability of the new model show that significant improvements are achieved. Improvements are specifically observed in the prediction of: (I) breaking point and the breaking wave height, (II) the consequent dissipation of the wave energy observed in the form of the crest level distribution throughout the surf zone, (III) the magnitude of the horizontal velocity near the free surface, and (IV) the TKE distribution in depth. Notably, the novel numerical model does not use any parametric criteria for detecting the inception of breaking, thus it does not need calibration for different flow circumstances. Also, since no special treatments, such as hydrostatic pressure assumptions at the front face of the breaking waves are considered, the new model well captures the breaking-induced dissipation while giving a more accurate estimation of the dynamic pressure.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277492

Fluid dynamics in the functional foregut of xylem-sap feeding insects: A comparative study of two Xylella fastidiosa vectors
JOURNAL OF INSECT PHYSIOLOGY
Autore/i: Ranieri, E.; Zitti, G.; Riolo, P.; Isidoro, N.; Ruschioni, S.; Brocchini, M.; Almeida, R. P. P.
Classificazione: 1 Contributo su Rivista
Abstract: Xylem sap sucking insects are adapted to ingest fluids under tension. Although much has been learned about such feeding strategy, this adaptation still poses several unresolved questions, including how these insects ingest against strong xylem sap tension. Xylem sap-feeding insects are vectors of the plant pathogenic xylem-limited bacterium Xylella fastidiosa. This bacterium colonizes the cuticular lining of the foregut of vectors in a persistent manner. We used micro-computed tomography and scanning electron microscopy to investigate the foregut morphometry of two X. fastidiosa vector species: Philaenus spumarius and Graphocephala atropunctata (Hemiptera: Aphrophoridae and Cicadellidae, respectively). On the basis of morphometric data, we built a hydrodynamic model of the foregut of these two insect species, focusing on the precibarium, a region previously shown to be colonized by X. fastidiosa and correlated with pathogen acquisition from and inoculation to plants. Our data show that space in the P. spumarius functional foregut could potentially harbor twice as many cells as similar space in G. atropunctata, although the opposite trend has been observed with biological samples. Average flow velocity of ingested fluid depended on the percentage of the cibarium volume exploited for suction: if the entire volume were used, velocities were in the range of meters per second. In contrast, velocities on the order of those found in the literature (about 10 cm/s) were attained if only 5% of the cibarium volume were exploited. Simulated bacterial colonization of the foregut was analyzed in relation to hydrodynamics and pressure needed for insects to ingest. Our model is designed to represent the diameter reduction of the food canal in both insect species when infected with X. fastidiosa. Results indicated that full bacterial colonization significantly increased the mean sap-sucking flow velocity. In particular, the colonization increased the maximum section-averaged velocity in the G. atropunctata more than two times and the net pressure needed to mantain the flow in the precibarium when colonized is relevant (about 0.151 MPa) if compared to a standard xylem sap tension (1 MPa). Bacterial colonization also influenced the sucking process of the G. atropunctata, by hindering the formation of a recirculation zone (or eddy), that characterizd the flow in the distal part of the precibarium when bacteria were absent. On the other hand, considering the pressure the insect must generate to feed, X. fastidiosa colonization probably influences fitness of the G. atropunctata more than that of P. spumarius.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273201

An analytical description of the energy balance in turbulent, round, free jets
AIP ADVANCES
Autore/i: Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: This brief contribution provides a quantification of the terms of the turbulent kinetic energy transport equation for a round steady turbulent free jet. The analysis is based on the assumption of flow self-similarity, and it is performed by means of a simple analytical asymptotic analysis. The results are in good agreement with the experimental findings of Panchapakesan and Lumley [J. Fluid Mech. 246, 197-223 (1993)] and with the large eddy simulations of Bogey and Bailly [J. Fluid Mech. 627, 129-160 (2009)], hence providing a theoretical interpretation of such findings.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287979

Wave-induced vortex generation around a slender vertical cylinder
PHYSICS OF FLUIDS
Autore/i: Antolloni, Giulia; Jensen, Atle; Grue, John; Riise, Bjørn H.; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Experimental results of wave-induced vortex generation around a slender, vertical cylinder are discussed. Coherent vortices appear in long waves (kR = 0.1) (k wavenumber, R cylinder radius) during the timing of the secondary load cycle, a strongly nonlinear component of the wave force acting on the cylinder, which is also measured. The secondary load cycle is present also in moderately long wave cases (kR = 0.3), where, however, there is no vortex formation. The measurement of vortex generation is enabled by Particle Image Velocimetry. The flow downstream the cylinder, in three horizontal planes at different depths is measured. The vortex formation that occurs in the long waves is attached to the cylinder in the form of thin vortex tubes. These appear symmetrically at angles of 40-45 degrees off the wave propagation direction. In one weak long wave case several very thin vortex tubes appear along the back side of the cylinder. Vortex diameters are 20 % of the cylinder diameter in four cases and 50 % of the cylinder diameter in one case. The measured vorticity emanates from the cylinder's boundary layer and is an order of magnitude stronger than to the vorticity caused by wave breaking. Wave breaking reduces the vortex strength. The fact that the secondary load cycle appears without and with flow separation effects indicates that the load cycle is a gravity wave phenomenon that scales with the Froude number, but that flow separation effects also contribute to the magnitude of such suction force.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277101

Hydrodynamics at a microtidal inlet: Analysis of propagation of the main wave components
ESTUARINE, COASTAL AND SHELF SCIENCE
Autore/i: Melito, Lorenzo; Postacchini, Matteo; Sheremet, Alex; Calantoni, Joseph; Zitti, Gianluca; Darvini, Giovanna; Penna, Pierluigi; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: The evolution of different wave components as they propagate within a microtidal inlet during a storm occurring from 24–26 January 2014 is analyzed, in order to improve knowledge on how microtidal river mouths typical of the Adriatic Sea behave. For the first time, the ”low-pass filter” mechanism previously ascertained at several macrotidal oceanic inlets around the world has been observed in the field with remarkably specific hydrodynamic conditions, i.e. low tide excursion, permanent connection with the sea and generally milder wave climate than in the ocean. Sea/swell (SS) waves were strongly dissipated before entering the river mouth, through the combined action of wave breaking due to reducing depths and opposing river currents enhanced by rainfall. Infragravity (IG) waves propagated upstream and significant IG wave heights of up to 0.4 m, about 13% of the local water depth, have been observed 400 m upriver (about 10 times the local SS peak wavelength) during storm climax. The IG wave energy here represented over 4% of the maximum offshore storm energy. IG wave components travelled upriver at estimated velocities between 3.6 m/s and 5.5 m/s (comparable with speeds of nonlinear long waves) during intense storm stages up to 600 m into the river channel (about 15 times the local SS peak wavelength), and are enhanced by tide-induced increase in water depths. It is estimated that tide-induced excursion accounted for about 80% of the total mean water elevation at storm peak at about 400 m into the river. Finally, tidal oscillations are detected up to 1.5 km upstream (about 40 times the local SS peak wavelength). This study highlights the dominance of astronomical tide over both wave setup and storm surge in controlling the upriver propagation of IG waves, even in a microtidal environment.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273197

Efficiency evaluation of a ductless Archimedes turbine: Laboratory experiments and numerical simulations
RENEWABLE ENERGY
Autore/i: Zitti, G.; Fattore, F.; Brunori, A.; Brunori, B.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: The aim of designing a new hydrokinetic turbine simple, cheap, environmentally friendly and suitable for installation in remote areas is pursued by studying the efficiency of an Archimedes turbine that exploits the kinetic energy of a water stream rather than an upstream-downstream difference in water head. First, the efficiency of a hydrokinetic Archimedes turbine has been studied using laboratory experiments for low TSR regimes. Subsequently, numerical simulations have been run to evaluate the performance coefficient of the turbine only (without frictional losses or blockage augmentation), and to extend the TSR range. Numerical simulations have allowed to produce the efficiency curve of the hydrokinetic Archimedes turbine in both aligned and inclined configurations. The obtained maximum performance coefficients have been compared with those of other hydrokinetic turbines currently in use and inspected through a parametric analysis dedicated to explore the practical applications of the proposed turbine.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273202

Wave-resolving shoreline boundary conditions for wave-averaged coastal models
OCEAN MODELLING
Autore/i: Memmola, F.; Coluccelli, A.; Russo, A.; Warner, J. C.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: Downscaling broadscale ocean model information to resolve the fine-scale swash-zone dynamics has a number of applications, such as improved resolution of coastal flood hazard drivers, modeling of sediment transport and seabed morphological evolution. A new method is presented, which enables wave-averaged models for the nearshore circulation to include short-wave induced swash zone dynamics that evolve at the wave group scale (i.e. averaged over the short waves). Such dynamics, which cannot be described, by construction through wave-averaged models, play a fundamental role in nearshore hydrodynamics and morphodynamics. The method is based on the implementation of a set of Shoreline Boundary Conditions (SBCs) in wave-averaged models. The chosen set of SBCs allows for proper computation of the short-wave properties at a mean shoreline (xl) taken as the envelope of the actual shoreline. The suitability of the approach is assessed through implementation of the SBCs into the Regional Ocean Modeling System (ROMS) coupled to a spectral wave model (InWave for IG waves and SWAN for wind waves). As the aim is to assess the viability of the approach, the SBCs are implemented only through a one-way coupling to ROMS (i.e. ROMS forcing the SBCs). Four different test cases – with constant, periodic and bichromatic offshore forcing – are run to assess the model performances. The main results of the analysis are: (a) the proposed SBCs can well reproduce the shoreline motion and swash zone dynamics in there for all chosen tests (RMSE and BIAS less than 20 % up to a cross-shore resolution of 4.0m (L0∕3 or L0∕5)) and (b) implementation of the SBCs allows ROMS to accurately simulate the swash zone flows even at a resolution 40 times coarser than that needed by ROMS with its own wet–dry routine to properly describe the same flows. The latter result clearly demonstrates the major computational advantage of using the proposed SBCs. We also show that most of the swash zone dynamics is due to the mean flow (i.e. incoming Riemann variable) and the local (at xl) wave height. However, especially in the case of bichromatic waves, the swash zone water volume content also seems to play a crucial role.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287978

Numerical modeling of flow and bed evolution of bichromatic wave groups on an intermediate beach using nonhydrostatic xbeach
JOURNAL OF WATERWAY PORT COASTAL AND OCEAN ENGINEERING-ASCE
Autore/i: Ruffini, G.; Briganti, R.; Alsina, J. M.; Brocchini, M.; Dodd, N.; Mccall, R.
Classificazione: 1 Contributo su Rivista
Abstract: This paper analyzes the modeling of the hydro- A nd morphodynamics of bichromatic wave groups on an intermediate beach with an initial 1:15 slope. The nonhydrostatic version of XBeach was used to simulate two incident wave conditions of the experiments carried out within the HYDRALAB-IV Coupled High Frequency Measurement of Swash Sediment Transport and Morphodynamic (CoSSedM) project. The chosen forcing conditions have different strengths of swash-swash interaction. A procedure was developed to generate boundary conditions for the model that are able to fully account for both the bound and free long waves measured during the experiments. Using the normalized root-mean-squared error as a measure, this paper finds a higher accuracy of the nonhydrostatic version of XBeach in simulating swash-swash interaction from the hydrodynamics point of view, and worse performances in capturing the details of intragroup sediment transport. Nevertheless, the model is able to distinguish the relative difference in offshore swash sediment transport among different types of swash-swash interaction, and it is overall more successful in simulating beach morphodynamics when the swash sediment transport is of the same order of magnitude as the surf zone one.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277100

Towards the simulation of flood evacuation in urban scenarios: Experiments to estimate human motion speed in floodwaters
SAFETY SCIENCE
Autore/i: Bernardini, G.; Quagliarini, E.; D'Orazio, M.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: Studies on flood risk assessment at urban scale are becoming increasingly oriented towards the use of evacuation simulation models for population's safety. However, such tools generally simplify human dynamics in floodwater conditions and need data to quantify proper individual's speed. Novel information on the above dynamics is here presented. A group of over 200 volunteers has been engaged in evacuation laboratory experiments carried out into an open channel. Results allow to estimate the pedestrian's isolated motion speed as a function of depth D [m] (in the range 20–70 cm) of floodwater, in both “walking” and “running” conditions. To this aim, experiments were carried out in still water. For each walking conditions and floodwater depth, correlations have been obtained between evacuation speed and age, individuals’ height, mass and body mass index. The existence of significant motion speed differences, depending on D, is underlined. In addition, general trends in evacuation speed reduction depending on the specific flood force per unit width M have been investigated and confirmed. It is also clarified how human physiology and kinematics (i.e. knee articulation) can induce specific speed-affecting effects depending on D. Such quantitative differences in motion discourage the use of fire or general-purpose databases for flood simulations, while such experimental data could be used as input for evacuation models to describe different evacuees’ walking types in evacuation procedure.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276195

Wave-forced dynamics in the nearshore river mouths, and swash zones
EARTH SURFACE PROCESSES AND LANDFORMS
Autore/i: Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: The role of wave forcing on the main hydro‐morphological dynamics evolving in the shallow waters of the nearshore and at river mouths is analyzed. Focus is mainly on the cross‐shore dynamics that evolve over mildly sloping barred, dissipative sandy beaches from the storm up to the yearly timescale, at most. Local and non‐local mechanisms as well as connections across three main inter‐related subsystems of the nearshore – the region of generation and evolution of nearshore bars, river mouths and the swash zone – are analyzed. The beach slope is a major controlling parameter for all nearshore dynamics. A local mechanism that must be properly described for a suitable representation of wave‐forced dynamics of all such three subsystems is the proper correlation between orbital velocity and sediment concentration in the bottom boundary layer; while specific dynamics are the wave–current interaction and bar generation at river mouths and the sediment presuspension at the swash zone. Fundamental non‐local mechanisms are both infragravity (IG) waves and large‐scale horizontal vortices (i.e. with vertical axes), both influencing the hydrodynamics, the sediment transport and the seabed morphology across the whole nearshore. Major connections across the three subsystems are the upriver propagation of IG waves generated by breaking sea waves and swash–swash interactions, the interplay between the swash zone and along‐river‐flank sediment transport and the evolution of nearshore sandbars.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/270464

Sandbar dynamics in microtidal environments: Migration patterns in unprotected and bounded beaches
COASTAL ENGINEERING
Autore/i: Melito, Lorenzo; Parlagreco, Luca; Perugini, Eleonora; Postacchini, Matteo; Devoti, Saverio; Soldini, Luciano; Zitti, Gianluca; Liberti, Luca; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Novel observations of bar features and migration patterns at three Italian sandy beaches in Senigallia (central Adriatic Sea) and Terracina (central Tyrrhenian Sea) are presented. While two of these beaches are unprotected, one is artificially embayed through the presence of a concrete jetty. Bar locations and motions are analysed with video imagery data sets from coastal monitoring stations. Wave climate from the Copernicus oceanographic model is used to correlate hydrodynamics and beach morphology. Clear net offshore migration (NOM) patterns are identified at all beaches, although exhibiting different response scales. At the low-slope beach of Senigallia (mean surf zone slope of 0.009) bars are more sensitive to seasonal changes in wave climate, with offshore shifts in winter and inactivity in summer. Mean annual migration rates of up to 0.26 m/day and 0.09 m/day are observed for outer and inner bars, respectively. No significant response to single storms is observed, except during a single NNE storm. No distinct erosive or accretive trend for the shoreline is evidenced. At the steep beach of Terracina (mean surf zone slope of 0.018), conversely, bars are strongly responsive to single storm events, with displacements of up to 25–50 m across a single storm. The mean inter-annual migration rate is 0.08 m/day for the single/outer bar, whereas a slight onshore trend (-0.02 m/day) for the newborn inner bar is established. The presence of an artificial jetty at the Misa river mouth in Senigallia, finally, leaves the bar system, typically oscillating around an equilibrium position, susceptible to larger seasonal oscillations and strong offshore migration due to two ESE storm events. Numerical simulations of nearshore circulation for two storms from different directions predict the birth of longshore currents, higher ratios of significant wave height to water depth, and stronger bottom orbital velocities over bars in case of the ESE storm, suggesting a greater tendency for offshore-directed sediment transport.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/283529

Numerical investigation on the effects of the pitch angle on the efficiency of an Archimedean-type turbine
proceeding of the 13th European Wave and Tidal Energy Conference (EWTEC 2019)
Autore/i: Zitti, Gianluca; Fattore, F.; Brunori, A.; Brunori, B.; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292652

A model chain approach for coastal inundation: Application to the bay of Alghero
ESTUARINE, COASTAL AND SHELF SCIENCE
Autore/i: Postacchini, Matteo; Lalli, Francesco; Memmola, Francesco; Bruschi, Antonello; Bellafiore, Debora; Lisi, Iolanda; Zitti, Gianluca; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Coastal inundation is an important threat for many nearshore regions worldwide, and has significantly increased in the last years also due to sea-level rise and augmented impact of extreme events, like sea storms. Many countries and regions have recently invested to overcome such problems, which commonly lead to structure damages, beach erosion and many other consequences. Numerical modeling is an important tool for coastal inundation prediction, being a valuable support for management issues to mitigate the inundation risk or suggest resilient solutions. The present work illustrates a novel approach, based on a numerical model chain that exploits a tide-surge-wave operational modeling system (Kassandra), a phase-averaged model (ROMS-SWAN) for the wave propagation towards the shore, and a phase-resolving solver (NSWE) for the prediction of runup and coastal inundation. Such a chain is applied to the bay of Alghero (Sardinia, Italy), where the results of the mentioned chain are compared to those obtained using, in place of the phase-averaged model, an analytical model for the wave propagation. Results confirm that both chain approaches provide comparable inundations, though the use of the analytical, more approximate (e.g., less accurate and reliable description of wave breaking dissipation), model suggests more severe conditions and larger flooded areas. Our contribution provides a methodological approach for an accurate and reliable estimate of coastal flooding.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263424

Long waves approaching the coast: Green’s law generalization
JOURNAL OF OCEAN ENGINEERING AND MARINE ENERGY
Autore/i: Lalli, Francesco; Postacchini, Matteo; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: The original Green’s relationship provides the amplitude of a long wave at a given water depth as a function of the amplitude in deeper waters, accounting for the wave shoaling, taken as a one-dimensional process, and neglecting both diffraction and refraction effects. An analytical application of Green’s law can only be made in case of simple bathymetries, monotonically increasing in the cross-shore direction and being longshore uniform. In the present work, a new formulation is proposed, based on Green’s law, for the direct calculation of the change in amplitude of a long wave that approaches the coast while traveling over a natural bathymetry, characterized by a general shape. Hence, the effects due to the ray curvature provided by the refraction/diffraction phenomena are accounted for. In detail, a generalization of Green’s law is proposed by introducing a numerically computed coefficient. Comparisons have been provided between the wave amplitude evolution, reconstructed using the proposed law, and the results of numerical simulations, run using a solver based on the solution of the shallow water equations. Although local effects due to obstacles are not properly captured, such comparisons reveal that the generalized Green’s law works well in the far field under different wave and complex morphological conditions.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273419

Monitoring for Coastal Resilience: A Project for Five Italian Beaches
Proceedings of the 2018 IEEE International Workshop on Metrology for the Sea
Autore/i: Melito, Lorenzo; Luca, Parlagreco; Perugini, Eleonora; Postacchini, Matteo; Zitti, Gianluca; Brocchini, Maurizio
Editore: IEEE
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents the COPEMAP project, fruit of a research collaboration between the Università Politecnica delle Marche and the Istituto Superiore per la Protezione e la Ricerca Ambientale. The project focuses on developing a methodology for the assessment of beach resilience as a function of both natural forcing (e.g. incoming wave fields) and natural protection (e.g. underwater sand bars). This is accomplished through simplified analyses of available video-monitoring data.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263465

Sustainable Engineering for Resilient Built and Natural Environments
The First Outstanding 50 Years of “Università Politecnica delle Marche”
Autore/i: Alici, Antonello; Bocci, Maurizio; Bonvini, Paolo; Brocchini, Maurizio; Calamai, Alessandro; Canestrari, Francesco; Capozucca, Roberto; Carbonari, Alessandro; Carbonari, Sandro; Cardone, Fabrizio; Clementi, Francesco; Clini, Paolo; Cocchi, Giammichele; Corvaro, Sara; Darvini, Giovanna; Davì, Fabrizio; Dezi, Luigino; Di Giuseppe, Elisa; D’Orazio, Marco; Ferretti, Maddalena; Ferrotti, Gilda; Gara, Fabrizio; Giretti, Alberto; Graziani, Andrea; Lancioni, Giovanni; Lemma, Massimo; Lenci, Stefano; Lorenzoni, Carlo; Malinverni, Eva Savina; Mancinelli, Alessandro; Mariano, Fabio; Mentrasti, Lando; Mondaini, Gianluigi; Montecchiari, Piero; Munafò, Placido; Naticchia, Berardo; Postacchini, Matteo; Quagliarini, Enrico; Quattrini, Ramona; Ragni, Laura; Serpilli, Michele; Soldini, Luciano; Virgili, Amedeo; Zampini, Giovanni
Editore: Springer
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/272866

Wave-induced morphodynamics and sediment transport around a slender vertical cylinder
ADVANCES IN WATER RESOURCES
Autore/i: Miozzi, Massimo; Corvaro, Sara; Alves Pereira, Francisco; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: We study the dynamics of a sandy bed around a slender vertical cylinder forced by progressive, non-linear water waves. The seabed evolves continuously under the effects of the up-welling, down-welling and rolling events induced by vortical coherent structures. In turn, these are closely connected to the shape of the seabed, which is modified by the scouring and/or the deposition of the sand. Starting from a flat seabed, progressive waves induce a rapid and transient modification of the bottom morphology towards a dynamically stable equilibrium state, which is the focus of this work. The dynamical equilibrium state is a function of the wave period and is reached when the seabed morphology is not substantially altered. We describe such a state by an Eulerian in-phase analysis of the sand particle motion, inferred from Lagrangian data collected over a large number of wave passages. This analysis relies on the use of the defocusing digital PIV technique (DDPIV), for the first time applied to the specific flow of interest here. On the basis of the Eulerian analysis, the triggering of the key-events (up- and down-welling, rolling) over the wave phase is captured by identifying, through the Q > 0 criterion, the coherent flow structures responsible for the events. This analysis is coupled with the description of the sediment trajectories, analyzed in a Lagrangian manner and effectively assessing how and where the solid phase is transported during the key-events. Five main mobilization/transport mechanisms have been identified, three during the onshore flow and two during the offshore flow: (i) generation of a coherent structure reminiscent of a horseshoe vortex at the toe, (ii) intense scouring at the top of the flatbed region, (iii) vortex shedding in the wake during direct (onshore) flow, (iv) shear crossflow on the lee-side of the cylinder and (v) large vertical shearing in the flatbed region during the reverse (offshore) flow. At flow reversal, this shearing mechanism impacts on a significant area of sediments in the incoming region of the flow.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/254962

Research and Engineering for Resilient Infrastructures and Environment Protection
The First Outstanding 50 Years of “Università Politecnica delle Marche”
Autore/i: Bocci, Maurizio; Brocchini, Maurizio; Canestrari, Francesco; Cardone, Fabrizio; Corvaro, Sara; Darvini, Giovanna; Ferrotti, Gilda; Graziani, Andrea; Lorenzoni, Carlo; Mancinelli, Alessandro; Postacchini, Matteo; Soldini, Luciano; Virgili, Amedeo
Classificazione: 2 Contributo in Volume
Abstract: We discuss the contribution of the research groups that work at UNIVPM in the field of infrastructure engineering to the design of resilient hydraulic and transportation infrastructures and related solutions for the protection of the environment. After recalling the long history of research and engineering intervention of the groups of Hydraulics and Transportation Infrastructures of UNIVPM, we show how the activities of such groups are becoming of increasing importance in response to the growing request of innovative solutions for resilient infrastructures (e.g. coastal protection and maritime structures, road and airport pavements) and environment protection (e.g. coastal and river flood, air pollution, waste recycling and materials reuse). Such activities have been recently boosted by the resources made available to the two groups through the “Dipartimenti di Eccellenza” award, which largely focuses on the issue of engineering for resilient built and natural environments. A projection in the future of the activities of above is also proposed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273420

Flooding Pedestrians’ Evacuation in Historical Urban Scenario: A Tool for Risk Assessment Including Human Behaviors
RILEM Bookseries
Autore/i: Bernardini, Gabriele; Postacchini, Matteo; Quagliarini, Enrico; D’Orazio, Marco; Brocchini, Maurizio
Editore: Springer Netherlands
Classificazione: 2 Contributo in Volume
Abstract: In the future, safety in historical city centers will be significantly affected by climate change-related disasters, such as floods. Risk assessment in these scenarios requires the combination of a series of factors: possible events characterization; urban layout configuration, its influence on flooding spreading and induced environmental modification; human factor, especially during first emergency phases. Historic urban scenario features (e.g.: compact urban fabrics; position near floodplains; possible inefficient early warning systems) additionally increase individuals’ risks. According to a “behavioral design” approach, developing flood evacuation simulation tools would help safety designers in assessing population’s exposure and then in suggesting emergency strategies to help citizens during such hazardous phases. This paper proposes a flooding evacuation simulation tool, which jointly represents the individuals’ evacuation motion towards safe areas, and the floodwaters spreading in the urban scenario. In particular, the simulator is founded on previous literature results concerning emergency behaviors and motion quantities (e.g.: evacuation speed as function of floodwaters flow) and adopts an agent-based model architecture. A part of the historic city center of Senigallia, an Italian city that suffered a significant flood in 2014, is chosen as application case-study to show tool capabilities. Results outline risk levels for individuals, and evidence critical points (in the urban space and during the time) for man-floodwaters-environment interactions (e.g.: being swept away by floodwaters). By evaluating probable evacuees’ choices in different scenarios, the tool is proposed to check the effectiveness of solutions for reducing evacuation process risks (e.g.: emergency planning; architectural elements development; interventions for floodwaters collection also in urban scenarios).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263425

Linear depth inversion sensitivity to wave viewing angle using synthetic optical video
COASTAL ENGINEERING
Autore/i: Perugini, Eleonora; Soldini, Luciano; Palmsten, Margaret L.; Calantoni, Joseph; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269388

Monitoring for Coastal Resilience: Preliminary Data from Five Italian Sandy Beaches
SENSORS
Autore/i: Parlagreco, Luca; Melito, Lorenzo; Devoti, Saverio; Perugini, Eleonora; Soldini, Luciano; Zitti, Gianluca; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Video-monitoring can be exploited as a valuable tool to acquire continuous, high-quality information on the evolution of beach morphology at a low cost and, on such basis, perform beach resilience analyses. This manuscript presents preliminary results of an ongoing, long-term monitoring programme of five sandy Italian beaches along the Adriatic and Tyrrhenian sea. The project aims at analyzing nearshore morphologic variabilities on a time period of several years, to link them to resilience indicators. The observations indicate that most of the beach width variations can be linked to discrete variations of sandbar systems, and most of all to an offshore migration and decay of the outermost bars. Further, the largest net shoreline displacements across the observation period are experienced by beaches with a clear NOM (Net Offshore Migration)-type evolution of the seabed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/265226

On a layer model for spilling breakers: A preliminary experimental analysis
EUROPEAN JOURNAL OF MECHANICS. B, FLUIDS
Autore/i: Lucarelli, A.; Lugni, C.; Falchi, M.; Felli, M.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: Accurate and reliable experimental data of a sloshing-induced, rapidly-evolving spilling breaker, are used to understand the specific physics of this phenomenon and to partially evaluate a simplified analytical model by Brocchini and co-workers (Brocchini , 1996; Misra et al., 2004, 2006). Such model is based on a three-layer structure: an underlying potential flow, a thin, turbulent single-phase layer in the middle and a turbulent two-phase layer (air–water) on the upper part. The experiments were carried out by using a 3 m long, 0.6 m deep and 0.10 m wide tank, built in Plexiglas and forced through an hexapode system, this allowing for an high accuracy of the motion. Mean and turbulent kinematic quantities were measured using the Particle Image Velocimetry (PIV) technique. To ensure repeatability of the phenomenon, a suitable breaker event was generated to occur during the first two oscillation cycles of the tank. The tank motion was suitably designed using a potential (HPC) and a Navier–Stokes solver. The latter, was useful to understand the dimension of the area of interest for the measurements. The evolution of the breaker is described in terms of both global and local properties. Wave height and steepness show that after an initial growth, the height immediately decays after peaking, while the wave steepness remains constant around 0.25. The evolution of the local properties, like vorticity and turbulence, vortical and turbulent flows displays the most interesting dynamics. Two main stages characterize such evolution. In stage (1), regarded as a ‘‘build-up’’ stage, vorticity and TKE rapidly reach their maximum intensity and longitudinal extension. During such stage the thickness of the single-phase turbulent region remains almost constant. Stage (2), is regarded as a ‘‘relaxation’’ stage, characterized by some significant flow pulsation till the wave attains a quasi-steady shape. In support to the analytical, three-layer model of Brocchini and co-workers it is demonstrated that the cross-flow profile of the mean streamwise velocity U inside the single-phase turbulent layer is well represented by a cubic polynomial. However, differently from available steadystate models the coefficient of the leading-order term is function of time: A = A(s, t). During stage (1) a fairly streamwise-uniform distribution of U is characterized by A(s, t) ≈ 1, while during stage (2) U is less uniform and A varies over a much larger range.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/264189

BATHYMETRY AND WAVE FIELD ESTIMATE USING A RADAR/NSP APPROACH: A NUMERICAL ANALYSIS
Atti del XXXVI Convegno Nazionale di Idraulica e Costruzioni Idrauliche
Autore/i: Ludeno, Giovanni; Postacchini, Matteo; Lugni, Claudio; Soldovieri, Francesco; Serafino, Francesco; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263429

A new video monitoring station along the Adriatic coast
XXXVI Convegno nazionale di Idraulica e Costruzioni Idrauliche
Autore/i: Perugini, Eleonora; Soldini, Luciano; Palmsten, Margaret L.; Calantoni, Joseph; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/266318

MODELLING HUMAN MOTION IN FLOOD EVACUATION: PRELIMINARY EXPERIMENTAL RESULTS
Atti del XXXVI Convegno Nazionale di Idraulica e Costruzioni Idrauliche
Autore/i: Postacchini, Matteo; Ascenzi, MARIA BEATRICE; Ramona, Bruni; Finizio, Fiorenza; Bernardini, Gabriele; Quagliarini, Enrico; Brocchini, Maurizio; D'Orazio, Marco
Classificazione: 2 Contributo in Volume
Abstract: Human behaviors in flood emergency affect individuals’ safety levels in urban scenarios. Evacuation simulators are needed to fully perform risk assessment and risk-reduction solutions evaluations. Volunteers are engaged in laboratory experiments to propose floodwaters-evacuation motion relations. A mannequin (representing an adult) is used for determining human stability limits in floodwaters. Preliminary results are compared to previous works and relations could be added to evacuation simulators.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263430

FLOOD IMPACTS ON BUILDINGS: FIRST EXPERIMENTAL AND NUMERICAL RESULTS
Proceedings del XXXVI Convegno Nazionale di Idraulica e Costruzioni Idrauliche
Autore/i: Brocchini, Maurizio; Capozucca, Roberto; Clementi, Francesco; Darvini, Giovanna; Giordano, Ersilia; Lenci, Stefano; Postacchini, Matteo; Zitti, Gianluca
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263397

METODI E MODELLI PER L’ANALISI DELL’INONDAZIONE COSTIERA: UNO STUDIO PER LA BAIA DI ALGHERO
Atti del XXXVI Convegno Nazionale di Idraulica e Costruzioni Idrauliche
Autore/i: Lalli, Francesco; Bruschi, Antonello; Luisa Cassese, Maria; Di Manna, Pio; Lisi, Iolanda; Vittori, Eutizio; Memmola, Francesco; Postacchini, Matteo; Bellafiore, Debora; Bajo, Marco; Boy, Alessandra; Pillai, Alessandra; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263428

Wave-Current Interactions and Infragravity Wave Propagation at a Microtidal Inlet
e-Proceedings of the 3rd EWaS International Conference on "Insights of the Water-Energy-Food Nexus"
Autore/i: Melito, Lorenzo; Postacchini, Matteo; Sheremet, Alex; Calantoni, Joseph; Zitti, Gianluca; Darvini, Giovanna; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Recent studies have shown that wave blocking occurs at river mouths with strong currents typically preventing relatively short period sea and swell waves from propagating up the river. However, observations demonstrate that lower frequency waves, so-called infragravity waves, do pass through and propagate up the river, particularly during storm events. We present observations from the Misa River estuary of infragravity wave propagation up the river during storm conditions. A model of the complex nonlinear interactions that drive infragravity waves is presented. The results are discussed in the context of an observed river mouth bar formed in the lower reach of the Misa River.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/258992

ANALYSIS OF MIXING AT RIVER MOUTHS: THE ROLE OF MACROVORTICES AND SUB-GRID TURBULENCE
8th International Symposium on Environmental Hydraulics
Autore/i: Melito, Lorenzo; Postacchini, Matteo; Darvini, Giovanna; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: INTRODUCTION A good understanding of flow mixing is important for properly describing the morphodynamics of the nearshore and river mouths. In recent years the modeling of flow mixing in natural shallow water regions has seen improvement thanks to the increasing computational power and the development of reliable and feasible models for large eddies and sub-grid turbulence. We here investigate the interplay between macrovortices, i.e. large-scale vortices with vertical axes, typical of shallow water flows, and the sub-grid turbulence characterizing river mouth flows, where a river current interacts with incoming sea waves. Generation of macrovortices is ensured by differential breaking at an estuarine shoal, whose presence also allows for inspection of the role of complex bathymetries (Olabarrieta et al., 2014). To this end, numerical simulations of wave-current interaction are performed by means of a solver for wave propagation in shallow water by Brocchini et al. (2001), integrated with a simple Horizontal Large Eddy Simulation (HLES) model proposed by Grosso et al. (2007). THE NUMERICAL MODEL The numerical model used for the tests (Brocchini et al., 2001) is based on the Nonlinear Shallow Water Equations (NSWE) and implements the finite-volume Weighted Averaged Flux method. The model is modified to give account of the dynamics induced by a river discharging at sea, and allows for computation of the morphological evolution of the bottom through the weak hydro-morphodynamic coupling proposed by Postacchini et al. (2012). The model also implements a simple HLES model to consider, in an approximate fashion, the dissipative terms due to sub-grid turbulence, which would, otherwise, be neglected by a classic approach of the NSWE (Grosso et al., 2007). THE TESTS Similarly to the wave-current interaction tests performed in the work of Olabarrieta et al. (2014), we reproduce the interaction of a steady river jet with weak-to-strong waves over a bathymetry characterized by a large river mouth shoal, and the generation, organization and migration of macrovortices as function of the sub-grid turbulence (HLES eddy viscosity varied between 0 and 0.1). THE RESULTS The numerical simulations reveal a significant generation and offshore advection of macrovortices at the seaward edge of the mouth shoal. Important turbulent structures are also observed, during the initial stages of the motion, at the corners of the inlet mouth, where the canalized, intense river current spreads over the shoal and interacts with the quiescent sea waters; these transient vortices dissipate fairly rapidly. The activation of the HLES model does not seem to have significant effects on the transient inlet vortices, causing only a limited decrease in their intensity as the sub-grid turbulence increases. Conversely, the shoal macrovortices are more sensible to changes in sub-grid turbulence: their intensity sensibly decreasing as the eddy viscosity increases. Notably, use of eddy viscosity parameters of the order 10-1 suppresses the generation of macrovortices in the shoal zone. Further considerations on these mechanisms will be illustrated at the conference.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/270377

COHERENT VORTICAL STRUCTURES IN PLUNGING BREAKERS
Atti del XXXVI Convegno Nazionale di Idraulica e Costruzioni Idrauliche
Autore/i: De Serio, Francesca; Brocchini, Maurizio; Buriani, Federica; Corvaro, Sara; Mossa, Michele
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263388

Effects of the wave climate on a multiple sandbar system
Proceedings of the 5th IAHR EUROPE CONGRESS New Challenges in Hydraulic Research and Engineering
Autore/i: Perugini, E.; Soldini, L.; Lorenzoni, C.; Brocchini, M.; Palmsten, M. L.; Calantoni, J.
Editore: The International Association for Hydro-Environment Engineering and Research (IAHR)
Luogo di pubblicazione: Madrid
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/265534

EFFICIENCY EVALUATION OF AN ARCHIMEDEAN-TYPE HYDROKINETIC TURBINE IN A STEADY CURRENT
proceeding of the 13th International Conference on Hydrodynamics
Autore/i: Zitti, Gianluca; Brocchini, Maurizio; Fattore, F.; Brunori, A.; Brunori, B.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292654

An assessment of the roller approach for wave breaking in a hybrid finite-volume finite-difference Boussinesq-type model for the surf-zone
APPLIED OCEAN RESEARCH
Autore/i: Tatlock, Benjamin; Briganti, Riccardo; Musumeci, Rosaria E.; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: This paper investigates the application of the roller approach for breaking waves in a 1D hybrid finite-volume finite-difference weakly-nonlinear Boussinesq-type model. The vorticity transport equation is employed to model the movement of vorticity through the fluid. This allows vertical profiles of horizontal velocity and undertow to be computed. Previous implementations of this method caused numerical dissipation that influenced the physical behaviour of the breaking process. The use of a hybrid scheme overcomes this issue as the need to filter flow variables in the surf-zone is removed. Greater numerical stability increases the flexibility of the calibration parameters, allowing finer control over the breaking process and a more detailed investigation of the underlying physics. The mechanism used to dissipate energy during breaking is derived from physical principles and the Boussinesq equations are retained throughout the breaking procedure, providing a realistic description of the hydrodynamics throughout the surf-zone. The dissipative performance of the proposed model is discussed and compared with other state-of-the-art approaches, proving the feasibility and value of using a rotational roller model with a finite-volume finite-difference scheme to model surf-zone hydrodynamics with a Boussinesq-type model. Tests involving waves breaking on a sloping beach are performed to validate against results from physical experiments, demonstrating the model to be capable of accurately resolving profiles of the free surface, velocity and undertow. The resulting new model overcomes many of the issues encountered by previous Boussinesq solvers based on the same approach and provides significant improvements in the accuracy of predictions of breaking wave processes. The proposed approach is very flexible and can be used in any hybrid finite-volume finite-difference weakly-nonlinear Boussinesq-type model.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/255066

Hydro- and morpho-dynamics induced by a vertical slender pile under regular and random waves
JOURNAL OF WATERWAY PORT COASTAL AND OCEAN ENGINEERING-ASCE
Autore/i: Corvaro, Sara; Marini, Francesco; Mancinelli, Alessandro; Lorenzoni, Carlo; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: This paper proposes an experimental study of the hydro- and morpho-dynamics induced by a slender vertical pile fitted into a sandy seabed and forced by sea waves in finite waters. The scour depth at the pile and the seabed morphology around it were measured and analyzed for both regular and random wave forcing. Scour depths due to regular waves were compared to those predicted in a previous study, revealing good agreement. The maximum scour depth occurred at the lateral side of the pile for waves characterized by a Keulegan-Carpenter (KC) number smaller than 7–8 and behind the pile for waves with KC>7–8. Such a result revealed an asymmetric effect on the scour depth because of the weaker reversal flow. This behavior was more evident for nonlinear waves being crests larger than troughs and, as a consequence, vortices, responsible for the scour processes, became even more energetic around crest stages. To better understand the dynamics in front of, around, and behind the cylinder, pressure measurements were obtained to evaluate the generation and evolution of vortices. The pressure data showed that the adverse pressure gradient around the pile was higher than on the upstream of the pile. The analyses of the pressure data seemed to confirm that, if the forcing was only due to waves, the effect of the lee-wake vortices on the scour depth around the cylinder was stronger than that due to the horseshoe vortices. Finally, the practical stochastic method proposed by previous authors to compute the maximum scour depth around a vertical pile exposed to random waves was verified. The best adaptation between measured and predicted scour depths was obtained by taking into account approximately half of the highest waves (instead of one-tenth) over the threshold; such a condition is still cautionary for a practical point of view. A simplification of the previously discussed methodology was proposed in which the characteristic wave that generates the scour depth is defined.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263122

Experimental Setup for the Validation of the Bio-Inspired Thruster of an Ostraciiform Swimming Robot
2018 14th IEEE/ASME International Conference on Mechatronic and Embedded Systems and Applications, MESA 2018
Autore/i: Costa, D.; Callegari, M.; Palmieri, G.; Scaradozzi, D.; Brocchini, M.; Zitti, G.
Editore: Institute of Electrical and Electronics Engineers Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In the last two decades, bio-inspired solutions have been thoroughly investigated as a source of efficiency and manoeuvrability improvement for underwater robots. The possibility to design a machine capable of propelling itself like a marine animal strongly depends on the understanding of the mechanics principles underlying biological swimming. The adoption of advanced simulation and measurement techniques is then fundamental to investigate the fluid-structure interaction phenomena characterizing the locomotion of aquatic animals. To address this very ambitious objective, the Authors designed an experimental setup devised to investigate the propulsive performances of an ostraciiform swimming robot. The numerical simulations performed on an oscillating foil led to the design of a dedicated force sensor, able to allow a complete characterization of the bio-inspired thruster and its actuation mechanism. The experimental test campaign is still under development but the results of the preliminary tests are hereby provided
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/261561

Experimental and Numerical Investigation of Pre-Breaking and Breaking Vorticity within a Plunging Breaker
WATER
Autore/i: Diana De Padova, ; Brocchini, Maurizio; Buriani, Federica; Corvaro, Sara; Francesca De Serio, ; Michele, Mossa; Stefano, Sibilla
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/256838

Waves and Currents at a River Mouth: The Role of Macrovortices, Sub-Grid Turbulence and Seabed Friction
WATER
Autore/i: Melito, Lorenzo; Postacchini, Matteo; Darvini, Giovanna; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Numerical experiments of wave-current interaction have been performed to investigate the evolution and dissipation of horizontal large-scale vortical structures generated by differential wave breaking and current shearing at river mouths. Specific focus is on the role played by turbulence of scales smaller than the water depth and by seabed friction on the dissipation of the mentioned macrovortices. The analysis reveals two regions of turbulence generation: at the river mouth, and along the curved seaward boundary of the shoal. In the latter zone, macrovortices are formed due to differential wave breaking induced by the sudden variation in water depth and enhanced by opposing currents which favour wave steepening. Such vortices are then advected towards the shore. Among the dissipative mechanisms, dissipation induced by seabed friction is deemed dominant, in particular in the most shallow waters of the shoal. Sub-grid turbulence dissipation, conversely, is more efficient offshore, although exerting some effect also over the shoal when supported by the continuous action of waves.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/258065

Extra Strain Rates in an unsteady spilling breaking wave
SCIENTIFIC REPORTS
Autore/i: Lucarelli, Alessia; Lugni, Claudio; Falchi, Massimo; Felli, Mario; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: We analyze the extra strain rates that characterize a curved, thin mixing layer induced at an unsteady spilling breaker. We focus on the flow curvature, which induces some extra rates of strain that should be accounted for in algebraic-type turbulence closures. The comparison between the analytical formulation proposed by Brocchini and co-workers for a single-phase turbulent thin layer of fluid and the data, obtained from a Particle Image Velocimetry (PIV) dedicated experimental program, reveals that the order of magnitude of the extra rates of strain induced by the streamline curvature, is comparable with that of the simple shear. This differs from what observed for the geometric curvature terms and from what occurs at hydraulic jumps, typically used to model steady breakers.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/264187

Normalized Scalar Product Approach for Nearshore Bathymetric Estimation from X-Band Radar Images: An Assessment Based on Simulated and Measured Data
IEEE JOURNAL OF OCEANIC ENGINEERING
Autore/i: Ludeno, Giovanni; Postacchini, Matteo; Natale, Antonio; Brocchini, Maurizio; Lugni, Claudio; Soldovieri, Francesco; Serafino, Francesco
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/253030

A depth semi-averaged model for coastal dynamics
PHYSICS OF FLUIDS
Autore/i: Antuono, M.; Colicchio, G.; Lugni, C.; Greco, M.; Brocchini, M.
Classificazione: 1 Contributo su Rivista
Abstract: The present work extends the semi-integrated method proposed by Antuono and Brocchini [“Beyond Boussinesq-type equations: Semi-integrated models for coastal dynamics,” Phys. Fluids 25(1), 016603 (2013)], which comprises a subset of depth-averaged equations (similar to Boussinesq-like models) and a Poisson equation that accounts for vertical dynamics. Here, the subset of depth-averaged equations has been reshaped in a conservative-like form and both the Poisson equation formulations proposed by Antuono and Brocchini [“Beyond Boussinesq-type equations: Semi-integrated models for coastal dynamics,” Phys. Fluids 25(1), 016603 (2013)] are investigated: the former uses the vertical velocity component (formulation A) and the latter a specific depth semi-averaged variable, Upsilon (formulation B). Our analyses reveal that formulation A is prone to instabilities as wave nonlinearity increases. On the contrary, formulation B allows an accurate, robust numerical implementation. Test cases derived from the scientific literature on Boussinesq-type models—i.e., solitary and Stokes wave analytical solutions for linear dispersion and nonlinear evolution and experimental data for shoaling properties—are used to assess the proposed solution strategy. It is found that the present method gives reliable predictions of wave propagation in shallow to intermediate waters, in terms of both semi-averaged variables and conservation properties.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251393

Wave attenuation over porous seabeds: A numerical study
OCEAN MODELLING
Autore/i: Torres Freyermuth, Alec; Brocchini, Maurizio; Corvaro, Sara; Pintado Patiño, José Carlos
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251135

Prediction of scour depth at breakwaters due to non-breaking waves using machine learning approaches
APPLIED OCEAN RESEARCH
Autore/i: Pourzangbar, Ali; Brocchini, Maurizio; Saber, Aniseh; Mahjoobi, Javad; Mirzaaghasi, Masoud; Barzegar, Mohammad
Classificazione: 1 Contributo su Rivista
Abstract: Coastal structures may cease to function properly due to seabed scouring. Hence, prediction of the maximum scour depth is of great importance for the protection of these structures. Since scour is the result of a complicated interaction between structure, sediment, and incoming waves, empirical equations are notas accurate as machine learning schemes, which are being widely employed for the coastal engineering modeling. In this paper, which can be regarded as an extension of Pourzangbar et al. (2016), two soft computing methods, a support vector regression (SVR), and a model tree algorithm (M5'), have been implemented to predict the maximum scour depth due to non-breaking waves. The models predict therelative scour depth (Smax/H0) on the basis of the following variables: relative water depth at the toe ofthe breakwater (htoe/L0), Shields parameter (theta), non-breaking wave steepness (H0/L0), and reflection coef-ficient (Cr). 95 laboratory data points, extracted from dedicated experimental studies, have been used for developing the models, whose performances have been assessed on the basis of statistical parameters.The results suggest that all of the developed models predict the maximum scour depth with high preci-sion, the M5model performed marginally better than the SVR model and also allowed to define a set oftransparent and physically sound relationships. Such relationships, which are in good agreement withthe existing empirical findings, show that the relative scour depth is mainly affected by wave reflection.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247012

Investigation of the dynamic loads on a vertically oscillating circular cylinder close to the sea bed: The role of viscosity
JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING-TRANSACTIONS OF THE ASME
Autore/i: Pierro, Alessio; Tinti, Enrico; Lenci, Stefano; Brocchini, Maurizio; Colicchio, Giuseppina
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251394

Snow avalanches striking water basins: behaviour of the avalanche’s centre of mass and front
NATURAL HAZARDS
Autore/i: Zitti, Gianluca; Ancey, C.; Postacchini, Matteo; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: We study the behaviour of a low-density granular material entering a water basin by means of a simplified two-dimensional model, with the aim to understand the dynamics of a snow avalanche impacting a water basin like an alpine lake or a fjord. The low density of the impacting mass induces an uplift buoyancy force and, consequently, a complicated interaction between the solid and fluid phase. This paper provides an insight into the motion of the impacting mass, by presenting a simplified, two-dimensional model, where the snow is described by a low-density granular material. First, small-scale experiments, based on the Froude similarity with snow avalanches, are used to evaluate the motion of reference points of the impacting mass, i.e. the front (F), centre of mass (C) and deepest point (L). Then, applying the mass and momentum conservation principles to a fixed volume, we show that the mean motion of the impacting mass is similar to that of a damped oscillator. The stretch of the impacting mass motion is described through the motion of the reference points F and L.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/248897

Comparison between the wintertime and summertime dynamics of the Misa River estuary
MARINE GEOLOGY
Autore/i: Brocchini, Maurizio; Calantoni, Joseph; Postacchini, Matteo; Sheremet, Alex; Staples, Tracy; Smith, Joseph; Reed, Allen H.; Braithwaite III, Edward F.; Lorenzoni, Carlo; Russo, Aniello; Corvaro, Sara; Mancinelli, Alessandro; Soldini, Luciano
Classificazione: 1 Contributo su Rivista
Abstract: The Misa River on the Italian Adriatic coast is typical of the rivers that drain the Apennine Mountain range. The focus of this study, conducted in the late summer of 2013 and mid-winter of 2014, was to contrast the general wintertime-summertime dynamics in the Misa River estuarine systemrather than investigate specific dynamical features (e.g. offshore sediment transport, channel seiche, and flocculation mechanisms). Summertime conditions of the Misa River estuary are characterized by low freshwater discharge and net sediment deposition whereas, in the wintertime, the Misa River and estuary is characterized by high episodic freshwater discharge and net erosion and sediment export. Major observed differences between wintertime-summertime dynamics in the Misa River and estuary are a result of seasonal-scale differences in regional precipitation and forcing conditions driven largely by the duration and intensity of prevailing wind patterns that frequently change direction in summertime while keep almost constant directions for much longer periods in wintertime, thus generating major sea storms. Sediment deposition was observed in the final reach of the Misa River and estuary in the summertime. However, in the wintertime, large flood events led to sediment erosion and export in the final reach of the Misa River and estuary that, in conjunction with storm-wave-induced mud transport, led to sediment deposition at the river entrance and in the adjacent nearshore region. The seasonal cyclic pattern of erosion and deposition was confirmedwith bathymetric surveys of the final reach of the estuarine region. A critical component for the balance between summertime deposition and wintertime erosion was the presence of an underlying mat of organic deposits that limited the availability of sediments for erosion in winter, when massive debris transport occurs. Further, suspended cohesive sediments flocs were subjected to smaller hydrodynamic stresses in the summertime favoring depositionwithin the estuary. Conversely, during wintertime storms, flocswere subjected to larger hydrodynamic stresses favoring breakup into smaller flocs and deposition outside the estuary.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247010

A preliminary combined simulation tool for the risk assessment of pedestrians' flood-induced evacuation
ENVIRONMENTAL MODELLING & SOFTWARE
Autore/i: Bernardini, Gabriele; Postacchini, Matteo; Quagliarini, Enrico; Brocchini, Maurizio; Cianca, Caterina; D'Orazio, Marco
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251392

Prediction of non-breaking wave induced scour depth at the trunk section of breakwaters using Genetic Programming and Artificial Neural Networks
COASTAL ENGINEERING
Autore/i: Pourzangbar, Ali; Losada, Miguel A.; Saber, Aniseh; Ahari, Lida Rasoul; Larroudé, Philippe; Vaezi, Mostafa; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Scour may act as a threat to coastal structures stability and reduce their functionality. Thus, protection against scour can guarantee these structures’ intended performance, which can be achieved by the accurate prediction of the maximum scour depth. Since the hydrodynamics of scour is very complex, existing formulas cannot produce good predictions. Therefore, in this paper, Genetic Programming (GP) and Artificial Neural Networks (ANNs) have been used to predict the maximum scour depth at breakwaters due to non-breaking waves (S /Hmax nb). The models have been built using the relative water depth at the toe (h /L toe nb), the Shields parameter (θ), the non-breaking wave steepness (H /L nb nb), and the reflection coefficient (Cr), where in the case of irregular waves, Hnb=Hrms, Tnb=Tpeak and Lnb is the wavelength associated with the peak period (Lnb=Lp). 95 experimental datasets gathered from published literature on small-scale experiments have been used to develop the GP and ANNs models. The results indicate that the developed models perform significantly better than the empirical formulas derived from the mentioned experiments. The GP model is to be preferred, because it performed marginally better than the ANNs model and also produced an accurate and physically-sound equation for the prediction of the maximum scour depth. Furthermore, the average percentage change (APC) of input parameters in the GP and ANNs models shows that the maximum scour depth dependence on the reflection coefficient is larger than that of other input parameters.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247011

PROTEZIONE DELLO SCAVO AL PIEDE DI UN PALO VERTICALE
Atti del Convegno Nazionale di Idraulica e Costruzioni Idrauliche
Autore/i: Mancinelli, Alessandro; Corvaro, Sara; Lorenzoni, Carlo; Tondi, Maria Cristina; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/249690

HYDRODYNAMICS OF A MUDDY ESTUARINE ENVIRONMENT: SUMMERTIME VS WINTERTIME CONDITIONS
The 12th International Conference on Hydrodynamics
Autore/i: Brocchini, Maurizio; Calantoni, Joseph; Postacchini, Matteo; Reed, Allen; Lorenzoni, Carlo; Mancinelli, Alessandro
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The hydrodynamics of an estuarine environment characterized by cohesive sediments, has been studied through a pair of experimental campaigns performed at the mouth of the Misa River. The Misa River flows from the Apennine Mountains and enters the Adriatic Sea in Senigallia, a tourist town located on the Mid-East coast of Italy. The estuary of the Misa River has characteristics of a field-scale laboratory; the final reach is highly engineered with containment structures. Consequently, it was chosen as a suitable site for the experiments undertaken during the EsCoSed (“Estuarine Cohesive Sediment”) Project. The estuarine environment of the Misa River was observed during both summertime and wintertime experiments. The hydrodynamics was monitored using both Eulerian (e.g., bottom moored platforms at both the river-bed and sea-bed with high-resolution ADCPs recording velocity profiles) and Lagrangian (e.g., surface drifters) instrumentation, allowing for the characterization of the flow field during very different flow conditions. The climate occurring before and during the investigated periods has also been analyzed through use of numerical simulations, wave buoy measurements, and tide gauges. A comparative analysis between summertime and wintertime conditions, focused on wave-current forcing and local estuarine hydrodynamics, is underway. The preliminary results highlight the control of wind direction on the observed hydrodynamics. During the summertime the wind frequently changes direction. Conversely, during wintertime the wind direction remains fairly constant leading to severe storms. The extreme wintertime events generate intense sediment transport driving morphologic change.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247222

MORPHODYNAMICS AROUND A SLENDER CYLINDER UNDER A WAVY BOUNDARY LAYER
Proceedings of ICMF 2016 - 9th International Conference on Multiphase Flow
Autore/i: Corvaro, Sara; Brocchini, Maurizio; Miozzi, Massimo; Pereira, Francisco Alves; Lorenzoni, Carlo; Mancinelli, Alessandro; Tondi, Cristina
Editore: Associazione Italiana di Ingegneria Chimica
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/249055

Escosed: Observations of Morphodynamics during Bora at the Mouth of the Misa River
International Conference on Multiphase Flow - ICMF 2016
Autore/i: Calantoni, J.; Sheremet, A.; Brocchini, Maurizio; Postacchini, Matteo
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The shallow mouth of the Misa River, Senigallia, Italy is exposed to wind and waves from the Adriatic Sea and is vulnerable to morphodynamic activity during even moderate storm events (e.g., winter Bora). Sediment loads and transport patterns may be strongly influenced by the confluence of fine cohesive suspended sediment contained in the discharge from the river mixing with coarser sandy material stirred up by waves impinging on the river mouth. Observations of rapid changes in bed elevation along a transect extending offshore of the river mouth were made using a combination of instruments deployed from 23-27 January 2014 at two locations in roughly 5 m water depth and 6 m water depth. At the 5 m water depth location over 0.4 m of deposition was observed roughly during a 6-hour period. Similarly, at the 6 m water depth location nearly 0.2 m of deposition was observed roughly over a 6-hour period with approximately a two-hour time lag. The onset of deposition was concurrent with a change in direction of the mean currents at both locations and a change in direction of wave skewness observed at the 5 m water depth location. We hypothesize that sandbar migration was responsible for the observed changes in bed elevation at both locations. Our analysis will focus on sediment transport modeling to explain rates of deposition and time lag of the observed changes in bed elevation at the 5 m and 6m water depth locations.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247228

Condizioni al Contorno di Riva Morfodinamiche: Alcuni Aspetti della Metodologia di Validazione
Atti del XXXV Convegno Nazionale di Idraulica e Costruzioni Idrauliche
Autore/i: Perugini, E.; Postacchini, Matteo; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247227

FLOW DYNAMICS OF WAVES PROPAGATING OVER DIFFERENT PERMEABLE BEDS
Proceedings of "35th Conference on Coastal Engineering" - ICCE2016
Autore/i: Corvaro, Sara; Mancinelli, Alessandro; Brocchini, Maurizio
Editore: Patrick Lynett
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/249063

Advances in numerical modelling of swash zone dynamics
COASTAL ENGINEERING
Autore/i: Briganti, Riccardo; Torres Freyermuth, Alec; Baldock, Tom E.; Brocchini, Maurizio; Dodd, Nicholas; Hsu, Tian Jian; Jiang, Zhonglian; Kim, Yeulwoo; Pintado Patiño, Jose Carlos; Postacchini, Matteo
Classificazione: 1 Contributo su Rivista
Abstract: We present a comprehensive and critical review of work on the numerical modelling of swash zone processes between 2005 and 2015. A wide range of numerical models has been employed for the study of this region and, hence, only phase-resolving approaches (i.e., depth-averaged and depth-resolving models) are analyzed. The current advances in the modelling of swash zone processes are illustrated by comparing different numerical models against laboratory experiments of a dam-break-driven swash event. Depth-averaged and depth-resolving models describe well the swash flow for both coarse sand and gravel impermeable beach cases. Depth-averaged models provides a practical tool for engineering use, whereas depth-resolving models improve the flow description, especially for the backwash phase, with a significantly higher computational cost. The evolution and magnitude of bed shear stresses predicted by all models is reasonable when compared with laboratory estimates based on the log-law. However, differences between modelling approaches cannot be rigorously evaluated owing to the uncertainty in shear stress estimates while employing such approximation. Furthermore, small-scale processes, such as turbulence evolution, are investigated with depth-resolving models, finding differences between the two-dimensional and three-dimensional approaches. Numerical models allow us to investigate other processes such as beach morphology changes, the evolution of the turbulence coherent structures, and the infiltration/exfiltration effects on the swash flow. A discussion on the advantages and limitations of each model is presented. The future of swash zone modelling depends on the increase of the computational power and, more importantly, on the improvement of the current capability to obtain intra-wave measurements for model validation, calibration, and greater resolution of physical processes.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/236355

Experiments on the impact of snow avalanches into water
Sustainable Hydraulics in the Era of Global Change - Proceedings of the 4th European Congress of the International Association of Hydroenvironment engineering and Research, IAHR 2016
Autore/i: Zitti, Gianluca; Ancey, C.; Postacchini, Matteo; Brocchini, Maurizio
Editore: CRC Press/Balkema
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The number of anthropized reservoirs threatened by snow avalanches is steadily increasing and impulse waves caused by avalanche impact are becoming a considerable risk for such basins. The dynamics of the impact of a snow avalanche into a water body is studied through laboratory experiments, where a granular material, with solid density slightly lower than that of the water, is used to simulate the buoyant behaviour of the snow. The proposed experimental model shares many similarities with those used to investigate the impact of landslides into water bodies (e.g., see Fritz et al. 2003a, Fritz et al. 2003b), but it also clarifies the differences between the impact of an avalanche and that of a landslide: while a landslide typically reaches the bottom of the water body, because of its high constant density, in the present experiments a floating motion of the impacted mass has been observed. The wave generation and its propagation are acquired by high-frequency cameras placed along the flume. Some preliminary results on wave amplitude/height decay and on wave celerity state the strongly non-linear behaviour of the generated wave. Further, their comparison with the corresponding predictive relations proposed for the case of landslides (Heller and Hager 2010) highlights a different wave decay and celerity evolution in the proximity of the impact.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247223

Experimental study of the short-term efficiency of different breakwater configurations on beach protection
JOURNAL OF OCEAN ENGINEERING AND MARINE ENERGY
Autore/i: Lorenzoni, Carlo; Postacchini, Matteo; Brocchini, Maurizio; Mancinelli, Alessandro
Classificazione: 1 Contributo su Rivista
Abstract: A campaign of experimental tests on a 2D movable-bed physical model, reproducing an Italian beach on the Adriatic Sea, has been performed in the wave flume of the “Laboratorio di Idraulica e Costruzioni Marittime” of the Università Politecnica delle Marche (Ancona, Italy), with the aim to assess the fundamental features of various breakwater configurations to be used in a beach-defence system typical of sandy, low-coastline beaches. Three emerged and three submerged configurations of rubble-mound detached breakwaters, for beach protection, placed at different distances from the shore, were tested, as well as a free beach configuration. The short-term hydrodynamic performances of the different configurations were assessed using as forcing some typical real-life intense sea-storm conditions. Wave transmission and beach protection efficiency under various intense wave conditions were obtained and related to some dimensionless parameters, amongst which a recently introduced one, χ, that combines both wave and breakwater properties. Transmission coefficients were found to be about 0.4 for emerged breakwaters and in the range 0.5–0.8 for submerged breakwaters. A net damping coefficient, defined as the wave height decay solely due to the effect of the breakwater, was measured as 0.2 for submerged breakwaters and 0.4 for the emerged ones. Further, submerged breakwaters induce an inshore mean water superelevation that increases with χ, whilst it decreases in the case of emerged breakwaters. Wave transmission is well represented by existing literature relations for both emerged and submerged breakwaters. Emerged breakwaters are more protective than submerged ones, but, at the same time, are more sensitive to changes in structure dimensions or positions. This is confirmed by the analysis of the momentum flux within the nearshore region, which is much larger for the submerged breakwaters. Such structures induce large swash-zone motions and sediment transport, comparable to those occurring at an unprotected beach.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247212

Sensors for Coastal Monitoring
JOURNAL OF SENSORS
Autore/i: Serafino, F.; Horstmann, J.; Nieto Borge, J. C.; Lugni, C.; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/235746

Lagrangian Observations of Waves and Currents From the River Drifter
IEEE JOURNAL OF OCEANIC ENGINEERING
Autore/i: Postacchini, Matteo; Centurioni, L. R.; Braasch, L.; Brocchini, Maurizio; Vicinanza, D.
Classificazione: 1 Contributo su Rivista
Abstract: The working principle and the capabilities of a new platform called the River Drifter are here presented. This technology has applications in the study of the hydrodynamics of coastal areas, rivers, and lakes. The River Drifter was designed for shallow water applications (1 m and deeper) to collect concurrent measurements of surface currents, three-dimensional velocity profiles underneath the device, water depth, and salinity. Here, we discuss how water level displacements can be inferred and used to measure the swell characteristics and to also correct the measured velocity. We also show how the local vorticity field can be computed. As an example application, we describe a study whose goal was to investigate the fate of a polluted river plume and how two River Drifters initially following the same path are characterized by very different final trajectories. The different behaviors of the two drifters are explained in terms of the local flow dynamics, which are strongly influenced by the seabed morphology, forcing the River Drifters to move in different directions.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/235745

60th anniversary special issue on significant advances in coastal engineering
JOURNAL OF WATERWAY PORT COASTAL AND OCEAN ENGINEERING-ASCE
Autore/i: Brocchini, Maurizio; Riggs, H. Ronald
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/244853

Shock trains on a planar beach: quasi-analytical and fully numerical solutions
NATURAL HAZARDS
Autore/i: Soldini, Luciano; Antuono, M.; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/239520

Assessing the Hydro-Morphodynamic Response of a Beach Protected by Detached, Impermeable, Submerged Breakwaters: A Numerical Approach
JOURNAL OF COASTAL RESEARCH
Autore/i: Postacchini, Matteo; Russo, Aniello; Carniel, Sandro; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Coastal areas host a large fraction of the world's population and are exposed to natural extreme events, which are a serious threat to human life, as well as to economies. For this reason, sea storms are increasingly the object of studies, and the design of traditional coastal defenses is being carried out in conjunction with modeling analyses. Relying on numerical simulations performed by means of an innovative shallow-water hydro-morphodynamic model, the present work explores the overall response of a protected beach to sea storms. Numerical tests evaluate the effects of sea states extracted from realistic sea storms having different spectral characteristics, as well as the influence on beach morphology of positioning shore-parallel, impermeable, submerged breakwaters. Simulation results revealed that, while erosion/accretion patterns depend weakly on the different sea state conditions, the morphodynamics induced around the barriers is strongly influenced by the breakwaters' positioning. More specifically, at least for the forcing here analyzed, bed variations were shown to increase when the structures are progressively located offshore; on the other hand, the swash zone morphology seems to be only weakly influenced by the positioning of the breakwaters. We also observed that for an increasing extension of the volume over which dissipative breaking mechanisms occur, a decreasing inshore erosion is accompanied by an equally fast decrease of offshore erosion. Analysis of the vorticity fields shows that breakwaters placed far from the shoreline induce an evolution of the vortices generated by breaking waves rather different from the one due to breakwaters placed closer to the shoreline (which can induce seaward flows through the gap, like rip currents).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/236356

Impulse waves generated by snow avalanches: Momentum and energy transfer to a water body
JOURNAL OF GEOPHYSICAL RESEARCH. EARTH SURFACE
Autore/i: Zitti, Gianluca; Ancey, Christophe; Postacchini, Matteo; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: When a snow avalanche enters a body of water, it creates an impulse wave whose effects may be catastrophic. Assessing the risk posed by such events requires estimates of the wave’s features. Empirical equations have been developed for this purpose in the context of landslides and rock avalanches. Despite the density difference between snow and rock, these equations are also used in avalanche protection engineering. We developed a theoretical model which describes the momentum transfers between the particle and water phases of such events. Scaling analysis showed that these momentum transfers were controlled by a number of dimensionless parameters. Approximate solutions could be worked out by aggregating the dimensionless numbers into a single dimensionless group, which then made it possible to reduce the system’s degree of freedom. We carried out experiments that mimicked a snow avalanche striking a reservoir. A lightweight granular material was used as a substitute for snow. The setup was devised so as to satisfy the Froude similarity criterion between the real-world and laboratory scenarios. Our experiments in a water channel showed that the numerical solutions underestimated wave amplitude by a factor of 2 on average. We also compared our experimental data with those obtained by Heller and Hager (2010), who used the same relative particle density as in our runs, but at higher slide Froude numbers.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247020

The EsCoSed Project: Summertime-Wintertime Evolution of the Misa River Estuarine Environment
Atti del XXII Congresso AIMETA
Autore/i: Brocchini, Maurizio; Joseph, Calantoni; Allen H., Reed; Alex, Sheremet; Tracy, Staples; Joseph, Smith; Postacchini, Matteo; Ed, Braithwaite; Tim, Kooney; Lorenzoni, Carlo; Russo, Aniello; Mancinelli, Alessandro; Soldini, Luciano; Corvaro, Sara; Coluccelli, Alessandro; Paroncini, Paolo
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/233514

Morphodynamic shoreline boundary conditions: A preliminary validation from laboratory experiments
Proceedings of the International Offshore and Polar Engineering Conference
Autore/i: Brocchini, Maurizio; Postacchini, Matteo
Editore: International Society of Offshore and Polar Engineers
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: At present the processes occurring in the Swash Zone (SZ) are disregarded by all available wave-averaged nearshore circulation models. Only recently a series of studies has proposed an approach to solve this problem by means of Shoreline Boundary Conditions (SBCs) obtained from integrating the Nonlinear Shallow Water Equations over the SZ width. While hydrodynamic conditions are a consolidated and validated theoretical tool, morphodynamic conditions (MSBCs) still require theoretical inspection and experimental validation. We here focus on a theoretical analysis of the problem, which, on the basis of available experimental data, aims at clarifying the role of short- and long-wave contributions to the mentioned MSBCs.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247224

Whole-wavelength description of a wave boundary layer with permeable wall
EXPERIMENTS IN FLUIDS
Autore/i: Miozzi, M.; Postacchini, Matteo; Corvaro, Sara; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: This paper describes the whole-wavelength, highly resolved velocity field statistics in an oscillatory boundary layer driven by gravity waves, evolving on both impermeable and permeable beds. Velocity data from PTV measurements are acquired in a small window and then extended to the whole wavelength by means of a new phase-locked slotting technique. This technique increases the robustness of statistics and resolution by improving the number of the data samples available for each spatial cell in the Eulerian representation of the oscillatory boundary layer. The into-and out-of-bed volume flux is evaluated and its effects on the velocity field are reported, together with its influence on vorticity evolution. The presence of coherent structures embedded in a shear-dominated scenario is emphasized. The Lagrangian flow features extracted by PTV are presented in the context of the generalized Lagrangian-mean theory. The Stokes drift vertical profile is estimated by comparing the Eulerian and Lagrangian velocities. A critical height-separating region where the volume flux due to ventilation has different effects on both orbital amplitudes and Stokes drift is found. This distance corresponds to the maximum height of the still-attached vorticity layer.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/227975

Local scour around structures and the phenomenology of turbulence
JOURNAL OF FLUID MECHANICS
Autore/i: Manes, Costantino; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: The scaling of the scour depth of equilibrium at the base of a solid cylinder immersed within an erodible granular bed and impinged by a turbulent shear flow is investigated here, for the first time, by means of the phenomenological theory of turbulence. The proposed theory allows the derivation of a predictive formula that (i) includes all the relevant non-dimensional parameters controlling the process, and (ii) contrary to commonly employed empirical formulae, is free front scale issues. Theoretical predictions agree very well with experimental data, shed light on unresolved issues on the physics of the problem, and clarify the effects of various dimensionless parameters controlling the scouring process.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/227977

Impulse waves generated by snow avalanches falling into lakes
E-proceedings of the 36th IAHR World Congress
Autore/i: Zitti, Gianluca; Ancey, Christophe; Postacchini, Matteo; Brocchini, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In recent years, the number of water reservoirs in high-altitude areas has increased. They are often used to provide water for various activities related with recreational (i.e. skiing) and production activities. Many of such reservoirs are threatened by snow avalanches. To investigate the phenomenon, an experimental study was carried out at the Ecole Polytechnique Fédérale de Lausanne using a prismatic 3m-long flume. A mass of buoyant particles, initially at rest, was released into a water flume down a 30°-sloping ramp. Its impact with the water surface was analyzed in detail. During the tests, the impacting mass, the water depth in the flume and the ramp length were changed. Both the dynamics of the granular mass at the impact zone and the wave generation induced by the impact were acquired using a high-frequency camera and accurately analyzed. An analysis of the wave propagation along the flume, also captured by two lower-speed cameras, was made by mean of numerical analyses based on a depth-averaged Boussinesq-type model. A theoretical analysis has also been undertaken to assess how the sub-aerial mass dynamics influences energy dissipation, and to identify the key variables of the problem, i.e. the velocity at impact, the shape of the water volume displaced during the impact, the depth of the center of the submerged mass and the percentage of submerged mass.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247225

Summertime conditions of a muddy estuarine environment: the EsCoSed project contribution
WATER SCIENCE AND TECHNOLOGY
Autore/i: Brocchini, Maurizio; Calantoni, J.; Reed, A. H.; Postacchini, Matteo; Lorenzoni, Carlo; Russo, Aniello; Mancinelli, Alessandro; Corvaro, Sara; Moriconi, Giacomo; Soldini, Luciano
Classificazione: 1 Contributo su Rivista
Abstract: As part of the Estuarine Cohesive Sediments (EsCoSed) project, a field experiment was performed in a highly engineered environment, acting as a natural laboratory, to study the physico-chemical properties of estuarine sediments and the associated hydro-morphodynamics during different seasons. The present contribution focuses on the results obtained from the summertime monitoring of the most downstream part of the Misa River (Senigallia, Italy). The measured hydrodynamics suggested a strong interaction between river current, wave forcing and tidal motion; flow velocities, affected by wind waves traveling upstream, changed significantly along the water column in both direction and magnitude. Surficial salinities in the estuary were low in the upper reaches of the estuary and exceeded 10 psu before the river mouth. Montmorillonite dominated the clay mineral assemblage, suggesting that large, low density flocs with high settling velocities (> 1 mms(-1)) may dominate the suspended aggregate materials.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/226471

Turbulence in Rivers
Rivers – Physical, Fluvial and Environmental Processes
Autore/i: Franca, M.; Brocchini, Maurizio
Editore: Springer International Publishing Switzerland
Luogo di pubblicazione: Cham, Heidelberg, New York, Dordrecht, Lndon
Classificazione: 2 Contributo in Volume
Abstract: The study of turbulence has always been a challenge for scientists working on geophysical flows. Turbulent flows are common in nature and have an important role in geophysical disciplines such as river morphology, landscape modeling, atmospheric dynamics and ocean currents. At present, new measurement and observation techniques suitable for fieldwork can be combined with laboratory and theoretical work to advance the understanding of river processes. Nevertheless, despite more than a century of attempts to correctly formalize turbulent flows, much still remains to be done by researchers and engineers working in hydraulics and fluid mechanics. In this contribution we introduce a general framework for the analysis of river turbulence. We revisit some findings and theoretical frameworks and provide a critical analysis of where the study of turbulence is important and how to include detailed information of this in the analysis of fluvial processes. We also provide a perspective of some general aspects that are essential for researchers/practitioners addressing the subject for the first time. Furthermore, we show some results of interest to scientists and engineers working on river flows.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/234417

Advances in fluid mechanics for offshore engineering: a modelling perspective
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A: MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
Autore/i: Brocchini, Maurizio; Faltinsen, O. M.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/205528

Gas cavity-body interactions: efficient numerical solution
COMPUTERS & FLUIDS
Autore/i: Colicchio, G.; Greco, M.; Faltinsen, O. M.; Brocchini, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: The paper investigates the interactions occurring between a gas cavity, the surrounding liquid and the nearby structures. In more detail, focus is in the characterization of the various dynamical phases (e.g. "acoustic phase" and "gas bubble phase") and in the design of a modelling approach aimed at minimizing the computational efforts needed to analyse the cases of gas cavities spatially close to the target structure. Hence, a domain decomposition (DD) strategy is proposed which enables efficient computations. Hyperbolic flow equations govern the flow evolution and, while the inner domain 1D solution is calculated by means of an HLL scheme for the fluxes and a 1st order time stepping, the outer domain 3D solution is achieved on the basis of a MUSCL scheme coupled with a 3rd order Runge-Kutta time stepping. Various comparative tests, based on use of the full-scale experimental data by Smith (1975), have been used to test the DD strategy. A simplified approach is, finally, proposed to be used for the complex case of multiple cavity explosions. Use of the approach reveals that the worst load scenario for the target structure occurs when all cavities explode simultaneously.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/226134