Moments conservation in adaptive Vlasov solver

We previously developed an adaptive semi-Lagrangian solver using a multiresolution analysis based on interpolets which are a kind of interpolating wavelets introduced by Deslauriers and Dubuc. This paper introduces a new multiresolution approximation for this solver which allows to conserve moments up to any order by using the lifting method introduced by Sweldens

Étude et développement d'un module de contrôle pour une plate-forme de simulation numérique

Ce travail a comme objectif d'étudier diverses solutions pour la mise en place d'une plate-forme de simulation numérique. Celle-ci doit pouvoir rassembler plusieurs programmes développés au sein du projet INRIA-CALVI, dont le but consiste en l'étude mathématique et numérique et la visualisation de divers problèmes issus essentiellement de la physique des plasmas et des faisceaux de particules. Ce rapport technique présente le développement d'un module de contrôle et propose une API (Application Programming Interface) à laquelle doivent se conformer les programmes destinés à tourner sur cette plate-forme. Il présente également le langage de script nommé python, ainsi que l'utilisation d'outils permettant d'étendre ses possibilités par des langages compilés

Quantum-classical transition in the electron dynamics of thin metal films

International audienceThe quantum electrons dynamics in a thin metal film is studied numerically using the self-consistent Wigner-Poisson equations. The initial equilibrium is computed from the Kohn-Sham equations at finite temperature, and then mapped into the phase-space Wigner function. The time-dependent results are compared systematically with those obtained previously with a classical approach (Vlasov-Poisson equations). It is found that, for large excitations, the quantum and classical dynamics display the same low-frequency oscillations due to ballistic electrons bouncing back and forth on the film surfaces. However, below a certain excitation energy (roughly corresponding to one quantum of plasmon energy \hbar\omega_{{\rm p}} ), the quantum and classical results diverge, and the ballistic oscillations are no longer observed. These results provide an example of a quantum-classical transition that may be observed with current pump-probe experiments on thin metal films

EXA2PRO programming environment:Architecture and applications

The EXA2PRO programming environment will integrate a set of tools and methodologies that will allow to systematically address many exascale computing challenges, including performance, performance portability, programmability, abstraction and reusability, fault tolerance and technical debt. The EXA2PRO tool-chain will enable the efficient deployment of applications in exascale computing systems, by integrating high-level software abstractions that offer performance portability and efficient exploitation of exascale systems' heterogeneity, tools for efficient memory management, optimizations based on trade-offs between various metrics and fault-tolerance support. Hence, by addressing various aspects of productivity challenges, EXA2PRO is expected to have significant impact in the transition to exascale computing, as well as impact from the perspective of applications. The evaluation will be based on 4 applications from 4 different domains that will be deployed in JUELICH supercomputing center. The EXA2PRO will generate exploitable results in the form of a tool-chain that support diverse exascale heterogeneous supercomputing centers and concrete improvements in various exascale computing challenges

A geological application in immersive virtual environments

International audienceThis paper presents a geological application in a virtual immersive environment : the ImmersiveGeological Pilot. This application allows a user to interactively build a structured geological model and its associated geological evolution scheme (a directed acyclic graph) by setting the various geological surfaces of the model one after the other in reverse chronological order, beginning with the youngest one. This immersive system runs on a workbench where users work directly within a virtual world. The main goal has been to prove that this geological application can benefit from working immersed and from 3D interaction techniques. After introducing the geological application on workstation, this paper describes the immersive version and presents the interaction techniques which have been used for selection, manipulation, navigation and application control. The resulting application in a 3D virtual environment is much more intuitive and ergonomic than the one on workstation

A parallel Vlasov solver using a wavelet based adaptive mesh refinement

We are interested in solving the Vlasov equation used to describe collective effects in plasmas. This nonlinear partial differential equation coupled with Maxwell equation describes the time evolution of the particle distribution in phase space. The numerical solution of the full three-dimensional Vlasov-Maxwell system represents a considerable challenge due to the huge size of the problem. A numerical method based on wavelet transform enables to compute the distribution function on an adaptive mesh from a regular discretization of the phase space. In this paper, we evaluate the costs of this recently developed adaptive scheme applied on a reduced one-dimensional model, and its parallelization. We got a fine grain parallel application that achieves a good scalability up to 64 processors on a shared memory architecture.

A task-based parallelization of a finite volume code for hyperbolic conservation law

International audienc

FPGA acceleration for HPC supercapacitor simulations

International audienceIn the search of more energy efficient computing devices that could be assembled to build future exascale systems, this study proposes a chip to chip comparison between a CPU, a GPU and a FPGA, as well as a scalability study on multiple FPGAs from two of the available vendors. The application considered here has been extracted from a production code in material science. This allows for the benchmarking of different implementations to be performed on a production test case and not just theoretical ones. The core algorithm is a matrix free conjugate gradient that computes the total electrostatic energy with an Ewald summation at each iteration. This paper depicts the original MPI implementation of the application, details a numerical accuracy study and explains the methodology followed as well as the resulting FPGA implementation based on MaxCompiler. The FPGA implementation using 40 bits floating point number representation outperforms the CPU implementation both in terms of computing power and energy usage resulting in an energy efficiency more than 15 times better. Compared to the GPU of the same generation, the FPGA reaches 60% of the GPU performance while the ratio of the performance per watt is still better by a factor of 2. Thanks to its low average power usage, the FPGA bests both fully loaded CPU and GPU in terms of number of conjugate gradient iterations per second and per watt. Finally, an implementation using oneAPI is described as well, showcasing a new development environment for FPGA in HPC

Design And Analysis Of Task-based Parallelization Of A Discontinuous Galerkin Euler Flow Solver On Heterogeneous Architectures

International audienc