35 research outputs found
Lagrange-flux schemes: reformulating second-order accurate Lagrange-remap schemes for better node-based HPC performance
No full textInternational audienceIn a recent paper [Poncet R., Peybernes M., Gasc T., De Vuyst F. (2016) Performance modeling of a compressible hydrodynamics solver on multicore CPUs, in “Parallel Computing: on the road to Exascale”], we have achieved the performance analysis of staggered Lagrange-remap schemes, a class of solvers widely used for hydrodynamics applications. This paper is devoted to the rethinking and redesign of the Lagrange-remap process for achieving better performance using today’s computing architectures. As an unintended outcome, the analysis has lead us to the discovery of a new family of solvers – the so-called Lagrange-flux schemes – that appear to be promising for the CFD community.Dans un article récent [Poncet R., Peybernes M., Gasc T., De Vuyst F. (2016) Performance modeling of a compressible hydrodynamics solver on multicore CPUs, in “Parallel Computing: on the road to Exascale”], nous avons effectué l’analyse de la performance d’un schéma de type Lagrange+projection à variables décalées ; cette classe de solveurs est très utilisée pour les applications d’hydrodynamique. Dans cet article, on s’intéresse à la reformulation des solveurs Lagrange-projection afin d’améliorer leur performance globale sur architectures de calcul standards. De manière inattendue, l’analyse nous a conduit vers la découverte d’une nouvelle famille de solveurs – appelés schémas Lagrange-flux – qui apparaissent comme très prometteurs dans la communauté CFD
Lagrange-Flux Schemes: Reformulating Second-Order Accurate Lagrange-Remap Schemes for Better Node-Based HPC Performance
No full textIn a recent paper [Poncet R., Peybernes M., Gasc T., De Vuyst F. (2016) Performance modeling of a compressible hydrodynamics solver on multicore CPUs, in “Parallel Computing: on the road to Exascale”], we have achieved the performance analysis of staggered Lagrange-remap schemes, a class of solvers widely used for hydrodynamics applications. This paper is devoted to the rethinking and redesign of the Lagrange-remap process for achieving better performance using today’s computing architectures. As an unintended outcome, the analysis has lead us to the discovery of a new family of solvers – the so-called Lagrange-flux schemes – that appear to be promising for the CFD community
ANALYSE DE PROBLÈMES MATHÉMATIQUES<br />DE LA MÉCANIQUE DES FLUIDES DE TYPE<br />BI-COUCHE ET À FRONTIÈRE LIBRE
No full textWe deal with some mathematical questions in fluid mechanics. The framework of this study is decomposed in two thematics : bi-layer models with free surface or rigid-lid hypothesis, analysis of problems defined in free boundary domains.Nous étudions dans ce document des problèmes mathématiques de la mécanique des fluides. Ce travail s'articule principalement autour de deux thèmes : les modèles bi-couches à surface libre ou à toit rigide, l'analyse de problèmes définis dans des domaines à frontière libre
ANALYSE DE PROBLÈMES MATHÉMATIQUES<br />DE LA MÉCANIQUE DES FLUIDES DE TYPE<br />BI-COUCHE ET À FRONTIÈRE LIBRE
No full textWe deal with some mathematical questions in fluid mechanics. The framework of this study is decomposed in two thematics : bi-layer models with free surface or rigid-lid hypothesis, analysis of problems defined in free boundary domains.Nous étudions dans ce document des problèmes mathématiques de la mécanique des fluides. Ce travail s'articule principalement autour de deux thèmes : les modèles bi-couches à surface libre ou à toit rigide, l'analyse de problèmes définis dans des domaines à frontière libre
ANALYSE DE PROBLÈMES MATHÉMATIQUES<br />DE LA MÉCANIQUE DES FLUIDES DE TYPE<br />BI-COUCHE ET À FRONTIÈRE LIBRE
No full textWe deal with some mathematical questions in fluid mechanics. The framework of this study is decomposed in two thematics : bi-layer models with free surface or rigid-lid hypothesis, analysis of problems defined in free boundary domains.Nous étudions dans ce document des problèmes mathématiques de la mécanique des fluides. Ce travail s'articule principalement autour de deux thèmes : les modèles bi-couches à surface libre ou à toit rigide, l'analyse de problèmes définis dans des domaines à frontière libre
CFD analysis of the turbulent flow in a PWR 5x5 rod bundle with staggered structural grids
No full textInternational audienc
CFD analysis of the turbulent flow in a PWR 5x5 rod bundle with staggered structural grids
No full textInternational audienc
Simulation of an oil slick movement using a shallow water model
No full textInternational audienceThe oil slick behaviour at the sea surface is studied using a bi layer shallow water model with free boundary condition. This model is solved by coupling the Arbitrary Lagrangian Eulerian method whit a Galerkin spatial discretization. A special basis that permit to obtain easily the solution by solving a scalar eigenvalue problem is proposed. An numerical experiments is presented in a realistic configuration
Simulation of an oil slick movement using a shallow water model
No full textInternational audienceThe oil slick behaviour at the sea surface is studied using a bi layer shallow water model with free boundary condition. This model is solved by coupling the Arbitrary Lagrangian Eulerian method whit a Galerkin spatial discretization. A special basis that permit to obtain easily the solution by solving a scalar eigenvalue problem is proposed. An numerical experiments is presented in a realistic configuration
Simulation of a spilled oil slick with a bi-layer shallow water model with free boundary
No full textInternational audienceIn this paper we present a new approach to describe the behaviour of a pollutant slick at the sea surface. To this end, we consider that the pollutant and the water are immiscible and we propose a two layer model where the lower layer corresponds to the water and the upper layer represents the pollutant. Since the dimension of the pollutant slick is generally much smaller than the domain occupied by the sea, we propose to compute the motion of the pollutant with a shallow water model with free boundary only in the domain occupied by the pollutant. To begin with, we verify numerically that the boundary conditions considered in introduction are valid. To do this, we solve the problem by extending it in a fixed domain. Then, to discretize in time the problem with free boundary, we use a ALE formulation coupled with the characteristic method. To solve the space discretized problem, we approximate the pollutant velocity by using a Galerkin method with a special basis which verifies the boundary conditions and simplifies significantly the resolution. Finally we test this work in a real situation: the dam of Calacuccia (Corsica)
