Adaptive mesh refinement method. Part 2: Application to tsunamis propagation

Numerical simulations of multi dimensional large scale fluid-flows such as tsunamis, are still nowadays a challenging and a difficult problem. To this purpose, a parallel finite volume scheme on adaptive unstructured meshes for multi dimensional Saint-Venant system is presented. The adaptive mesh refinement method is based on a block-based decomposition (called BB-AMR) which allows quick meshing and easy parallelization. The main difficulty addressed here concerns the selection of the mesh refinement threshold which is certainly the most important parameter in the AMR method. Usually, the threshold is calibrated according to the test problem to balance the accuracy of the solution and the computational cost. To avoid " hand calibration " , we apply an automatic threshold method based on the decreasing rearrangement function of the mesh refinement criterion. This method is applied and validated successfully to the one and two dimensional non homogeneous Saint-Venant system through several tsunamis propagation test cases

Ecoulement bi-fluide : Application à l’impact d’une vague solitaire

Nous cherchons à analyser le déferlement d’une  vague solitaire sur une plage en présence de macro-rugosités, par simulation numérique sur un code  volumes finis tridimensionnel. Le modèle bi-fluide à  faible Mach, déjà validé par des confrontations expérimentales, repose sur des schémas numériques  optimisés

Déferlement de vague : approche multi-pas

Nous simulons numériquement le déferlement de vagues par un modèle d'écoulement multi fluide à faible Mach grâce à une formulation explicite efficacement parallélisable. Le modèle repose sur un schéma par volumes finis de type Godunov du second ordre en temps et en espace et éventuellement un raidissement de l'interface. Nous introduisons une approche multi-pas qui autorise de conséquents gains en temps de calcul. Cette approche est validée par des confrontations expérience /simulation sur le déferlement de vague solitaire 2D sur plan incliné et la rupture de barrage 3D avec obstacle

Numerical simulations of wave breaking

This paper is devoted to the numerical simulation of wave breaking. It presents the results of a numerical workshop that was held during the conference LOMA04. The objective is to compare several mathematical models (compressible or incompressible) and associated numerical methods to compute the flow field during a wave breaking over a reef. The methods will also be compared with experiments

Simulation de la propagation et du déferlement d’une vague et de l’inondation d’unrèclif 2D: évaluation comparative des codes numérique pour la modélisation des tsunamis

In the framework of the French research project TANDEM dedicated to tsunami modelling, a series of benchmarks has been set up, addressing the various stages of a tsunami event: generation, propagation, run-up and inundation. We present here the results of five codes, involving both depth-averaged Boussinesq and fully 3D Navier-Stokes equations, aimed at being applicable to tsunami modelling. The codes are evaluated on a flow involving propagation, run-up, overtopping and reflection of the waves on two-dimensional reefs, and compared with the experimental data produced from a set of laboratory experiments carried out at the O.H. Hinsdale Wave Research Laboratory, Oregon State University (OSU, see Roeber et al., 2010 and Roeber and Chung, 2012).Dans le cadre du projet de recherche français TANDEM dédié à la modélisation de tsunamis, une série de tests a été mise enplace concernant les différentes étapes d'un tsunami : la génération, la propagation et l'inondation. Les résultats obtenus par cinq codessont présentés ici. Chacun d'eux utilise les équations de Boussinesq moyennées sur la profondeur et les équations de Naver-Stokes entrois dimensions adaptées à la modélisation de tsunamis. Ces codes sont évalués sur un écoulement impliquant la propagation, lasubmersion, et la réflexion des vagues sur un récif en deux dimensions. Une comparaison est effectuée à partir de données expérimentalesprovenant du laboratoire d'Hinsdale (O.H Hinsdale Wave Research Laboratory, Oregon State University, OSU, voir Roeber et al.,2010 etRoeber et Chung, 2012)

Numerical simulation of wave breaking

This paper is devoted to the numerical simulation of wave breaking. It presents the results of a numerical workshop that was held during the conference LOMA04. The objective is to compare several mathematical models (compressible or incompressible) and associated numerical methods to compute the flow field during a wave breaking over a reef. The methods will also be compared with experiments

Sometimes Sperm Whales (Physeter macrocephalus) Cannot Find Their Way Back to the High Seas: A Multidisciplinary Study on a Mass Stranding

BACKGROUND: Mass strandings of sperm whales (Physeter macrocephalus) remain peculiar and rather unexplained events, which rarely occur in the Mediterranean Sea. Solar cycles and related changes in the geomagnetic field, variations in water temperature and weather conditions, coast geographical features and human activities have been proposed as possible causes. In December 2009, a pod of seven male sperm whales stranded along the Adriatic coast of Southern Italy. This is the sixth instance from 1555 in this basin. METHODOLOGY/PRINCIPAL FINDINGS: Complete necropsies were performed on three whales whose bodies were in good condition, carrying out on sampled tissues histopathology, virology, bacteriology, parasitology, and screening of veins looking for gas emboli. Furthermore, samples for age determination, genetic studies, gastric content evaluation, stable isotopes and toxicology were taken from all the seven specimens. The animals were part of the same group and determined by genetic and photo-identification to be part of the Mediterranean population. Causes of death did not include biological agents, or the "gas and fat embolic syndrome", associated with direct sonar exposure. Environmental pollutant tissue concentrations were relatively high, in particular organochlorinated xenobiotics. Gastric content and morphologic tissue examinations showed a prolonged starvation, which likely caused, at its turn, the mobilization of lipophilic contaminants from the adipose tissue. Chemical compounds subsequently entered the blood circulation and may have impaired immune and nervous functions. CONCLUSIONS/SIGNIFICANCE: A multi-factorial cause underlying this sperm whales' mass stranding is proposed herein based upon the results of postmortem investigations as well as of the detailed analyses of the geographical and historical background. The seven sperm whales took the same "wrong way" into the Adriatic Sea, a potentially dangerous trap for Mediterranean sperm whales. Seismic surveys should be also regarded as potential co-factors, even if no evidence of direct impact has been detected

Validation of CFD models for tsunami simulation. TANDEM Projec

International audienc

Numerical analysis of the internal kinematics and dynamics of three-dimensional breaking waves on slopes

In this paper, we describe the development and validation of a numerical model based on coupling a higher-order Boundary Element Method (BEM) solution of fully nonlinear potential flow equations to a Volume Of Fluid (VOF) solution of Euler equations, in threedimensions (3D). The BEM solution is used as an initialization of the VOF/Navier-Stokes solver. Numerical simulations of breaking waves on sloping beaches for 2D (using an earlier similar model) and 3D flows are carried out. Finally, we simulate the breaking and post-breaking of a solitary wave over a sloping ridge in a three-dimensional numerical wave tank. Analysis of wave profiles and internal kinematics (velocity, vorticity, pressure) are presented. KEY WORDS: breaking ocean waves; nonlinear surface waves

Numerical analysis of the internal kinematics and dynamics of 3-D breaking waves on slopes

In this paper we describe the development and validation of a numerical model based on coupling a higher-order Boundary Element Method (BEM) solution of fully nonlinear potential flow equations to a Volume Of Fluid (VOF) solution of Euler equations, in 3 dimensions (3-D). The BEM solution is used as an initialization of the VOF/Navier-Stokes solver. Numerical simulations of breaking waves on sloping beaches for 2-D (using an earlier similar model) and 3-D flows are carried out. Finally, we simulate the breaking and post-breaking of a solitary wave over a sloping ridge in a 3-D numerical wave tank. We present an analysis of wave profiles and internal kinematics (velocity, vorticity, pressure). Copyright © by The International Society of Offshore and Polar Engineers