High performance computing challenges for research and industrial simulation codes

International audienceComputing hardware, from mobile devices to supercomputer clusters, is undergoing a paradigm shift : with the advent of multicore CPUs and accelerators (GPUs, Intel Xeon Phi), parallelism is becoming hierarchical, ubiquitous, heterogeneous, and more and more complex. Performance critical applications need new programming models to exploit efficiently such architectures. Guided by Herb Sutter analysis ([1], [2]) we draw practical conclusions for the design of future simulation codes, and the optimization of legacy codes

The VOLNA code for the numerical modelling of tsunami waves: generation, propagation and inundation

A novel tool for tsunami wave modelling is presented. This tool has the potential of being used for operational purposes: indeed, the numerical code \VOLNA is able to handle the complete life-cycle of a tsunami (generation, propagation and run-up along the coast). The algorithm works on unstructured triangular meshes and thus can be run in arbitrary complex domains. This paper contains the detailed description of the finite volume scheme implemented in the code. The numerical treatment of the wet/dry transition is explained. This point is crucial for accurate run-up/run-down computations. Most existing tsunami codes use semi-empirical techniques at this stage, which are not always sufficient for tsunami hazard mitigation. Indeed the decision to evacuate inhabitants is based on inundation maps which are produced with this type of numerical tools. We present several realistic test cases that partially validate our algorithm. Comparisons with analytical solutions and experimental data are performed. Finally the main conclusions are outlined and the perspectives for future research presented.Comment: 47 pages, 27 figures. Other author's papers can be downloaded at http://www.lama.univ-savoie.fr/~dutykh

Benchmark numérique des écoulements de Couette-Taylor turbulents

Les résultats issus de modèles de turbulence disponibles dans CFX et STAR CCM+ sont comparés aux mesures de Burin et al. (2010) ainsi qu'à de nouveaux calculs issus du modèle RSM d'Elena et Schiestel (1996) et d'un code LES basé sur le modèle de Smagorinsky dynamique développé au M2P2. Les paramètres géométriques (rapport d'aspect = 2.12, rapport des rayons = 0.35) sont ceux considérés dans l'expérience originale de Burin et al. Une comparaison détaillée entre les différentes approches est effectuée sur une large gamme du nombre de Reynolds (10000-400000)

Thermodynamic paths along streamlines of a single-phase transcritical CO2 vortex tube

Abstract: The Ranque-Hilsch vortex tube is at the center of a renewed interest as a robust expansion device and a useful energy supply for transcritical CO2 vapor compression systems. This paper gives insights into thermodynamic paths along streamlines in a transcritical CO2 vortex tube employing computational fluid dynamics (CFD). A pressure-based coupled solver along with a low-Reynolds number turbulence model and the Span-Wagner equation of state constitutes the present numerical framework. Transcritical expansions are carried out at several cold mass fractions and both outer and inner vortex flow streamlines are tracked in the pressure-specific volume and pressurespecific enthalpy diagrams. The results confirm that the transcritical CO2 vortex tube is the seat of energy and temperature separations but they are inverted. A correlation between the flow transcriticality and vortex tube temperature and energy separation inversions is observed.Communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Les stratégies de l’innovation collective : Communautés, organisations, territoires

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A posteriori limiting for 2D Lagrange plus Remap schemes solving the hydrodynamics system of equations

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Les stratégies de l’innovation collective : communautés, organistions, territoires

International audienc

Les stratégies de l’innovation collective : Communautés, organisations, territoires

International audienc

Lagrange-Flux Schemes: Reformulating Second-Order Accurate Lagrange-Remap Schemes for Better Node-Based HPC Performance

International 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