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Goutal N.,Electricite de France | Sainte-Marie J.,CNRS Saint-Venant Hydraulics Laboratory | Sainte-Marie J.,French Institute for Research in Computer Science and Automation
International Journal for Numerical Methods in Fluids | Year: 2011

The classical Saint-Venant system is well suited for the modeling of dam breaks, hydraulic jumps, reservoir emptying, flooding etc. For many applications, the extension of the Saint-Venant system to the case of non-rectangular channels is necessary and this section-averaged Saint-Venant system exhibits additional source terms. The main difficulty of these equations consists of the discretization of these source terms. In this paper we propose a kinetic interpretation for the section averaged Saint-Venant system and derive an associated numerical scheme. The numerical scheme-2nd order in space and time-preserves the positivity of the water height, and is well-balanced. Numerical results including comparisons with analytic and experimental test problems illustrate the accuracy and the robustness of the numerical algorithm. © 2010 John Wiley & Sons, Ltd. Source

Brigode P.,Electricite de France | Brigode P.,CNRS Transfers and Interactions in Hydrosystems and Soils | Bernardara P.,Electricite de France | Bernardara P.,CNRS Saint-Venant Hydraulics Laboratory | And 4 more authors.
International Journal of Climatology | Year: 2013

Classifications of atmospheric circulation patterns are useful tools to improve the description of the climate of a given region and the analysis of meteorological situations. In particular, weather pattern (WP) classifications could be used to improve the description of spatial heavy rainfall. Here, a bottom-up approach, previously used to build WP classification in France, is applied for the definition of a WP classification useful for the description of Austrian heavy rainfall. The optimal spatial extent and the optimal position of the geopotential fields to be taken into account for a WP classification is studied. The proposed WP classification is shown to be coherent with the general knowledge on synoptic situations responsible for heavy rainfall over Austria. Moreover, the classification has good performances in terms of heavy rainfall spatial description compared to 152 COST 733 classifications defined in the same region. In particular, we show that the choice of spatial extent of the geopotential fields, their position and their characteristics is relevant for capturing physical information on synoptic situations responsible for heavy rainfall and that it can improve WP classification performances. © 2012 Royal Meteorological Society. Source

Camenen B.,IRSTEA | van Bang D.P.,CNRS Saint-Venant Hydraulics Laboratory
Continental Shelf Research | Year: 2011

This paper deals with the sedimentation of highly concentrated sediment suspensions (cohesive as well as non-cohesive) and the beginning of the consolidation of cohesive sediments. Based on a comparison of existing empirical formulas and experimental data, the particle Reynolds number was shown to be of importance for the behaviour of particularly non-cohesive sediments. In addition it plays a role in determining whether one or two interfaces develop during the sedimentation phase. In the case of cohesive sediments, the estimation of the gelling concentration, although difficult, seems to be fundamental. Some suggestions on the estimation of the permeability coefficient and total settling function are then given in order to improve the modelling of the sedimentation and consolidation behaviour for concentrations close to the gelling concentration. © 2010 Elsevier Ltd. Source

Audusse E.,University of Paris 13 | Audusse E.,French Institute for Research in Computer Science and Automation | Bristeau M.-O.,French Institute for Research in Computer Science and Automation | Pelanti M.,French Institute for Research in Computer Science and Automation | And 3 more authors.
Journal of Computational Physics | Year: 2011

We present a multilayer Saint-Venant system for the numerical simulation of free surface density-stratified flows over variable topography. The proposed model formally approximates the hydrostatic Navier-Stokes equations with a density that varies depending on the spatial and temporal distribution of a transported quantity such as temperature or salinity. The derivation of the multilayer model is obtained by a Galerkin-type vertical discretization of the Navier-Stokes system with piecewise constant basis functions. In contrast with classical multilayer models in the literature that assume immiscible fluids, we allow here for mass exchange between layers. We show that the multilayer system admits a kinetic interpretation, and we use this result to formulate a robust finite volume scheme for its numerical approximation. Several numerical experiments are presented, including simulations of wind-driven stratified flows. © 2011 Elsevier Inc. Source

Chapelle D.,French Institute for Research in Computer Science and Automation | Gerbeau J.-F.,French Institute for Research in Computer Science and Automation | Sainte-Marie J.,French Institute for Research in Computer Science and Automation | Sainte-Marie J.,CNRS Saint-Venant Hydraulics Laboratory | Vignon-Clementel I.E.,French Institute for Research in Computer Science and Automation
Computational Mechanics | Year: 2010

This paper is motivated by the modeling of blood flows through the beating myocardium, namely cardiac perfusion. As in other works, perfusion is modeled here as a flow through a poroelastic medium. The main contribution of this study is the derivation of a general poroelastic model valid for a nearly incompressible medium which experiences finite deformations. A numerical procedure is proposed to iteratively solve the porous flow and the nonlinear poroviscoelastic problems. Three-dimensional numerical experiments are presented to illustrate the model. The first test cases consist of typical poroelastic configurations: swelling and complete drainage. Finally, a simulation of cardiac perfusion is presented in an idealized left ventricle embedded with active fibers. Results show the complex temporal and spatial interactions of the muscle and blood, reproducing several key phenomena observed in cardiac perfusion. © 2009 Springer-Verlag. Source

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