Team bacchus

Overall Objectives
Scientific Foundations
Application Domains
New Results
Contracts and Grants with Industry
Other Grants and Activities

Section: Other Grants and Activities

National initiatives

ASTER: Adaptive MHD Simulation of Tokamak Elms for iteR

Participants : Rémi Abgrall, Robin Huart, Pascal Hénon, Pierre Ramet [Corresponding member] , Hocine Sellama.

Grant: ANR-06-CIS

Dates: 2006 – 2010

Partners: CEA Cadarache.

Overview: The magneto-hydrodynamic instability called ELM for Edge Localized Mode is commonly observed in the standard tokamak operating scenario. The energy losses the ELM will induce in ITER plasmas are a real concern. However, the current understanding of what sets the size of these ELM induced energy losses is extremely limited. No numerical simulations of the complete ELM instability, from its onset through its non-linear phase and its decay, exist in literature. Recently, encouraging results on the simulation of an ELM cycle have been obtained with the JOREK code developed at CEA but at reduced toroidal resolution. The JOREK code uses a fully implicit time evolution scheme in conjunction with the PaStiX sparse matrix library. In this project it is proposed to develop and implement methods to improve the MHD simulation code to enable high-resolution MHD simulations of ELMs. The ELM simulations are urgently needed to improve our understanding of ELMs and to evaluate possible mechanism to control the energy losses. The improvements include adaptive mesh refinement, a robust numerical MHD scheme and refinable cubic Hermite finite elements. These developments need to be consistent with the implicit time evolution scheme and the PaStiX solver. The implicit scheme is essential due to the large variety of time scales in the MHD simulations. The new methods will be implemented and evaluated in the code RealfluiDS , developed by the BACCHUS team and the JOREK code to optimize the exchange of expertise on numerical methods and MHD simulations.

The project is a collaboration between the Departement de Recherche sur la Fusion Controlée (DRFC, CEA/Cadarache) and the Laboratoire Bordelais de Recherche en Informatique (LaBRI) and Mathématiques Appliquées de Bordeaux (IMB) at the University of Bordeaux 1.


PETAL: PETascaling ALgorithms for preconditioning used in scientific applications

Participants : Pascal Hénon [Corresponding member] , Jun-Ho Her, François Pellegrini, Pierre Ramet.

Grant: ANR Cosinus 2008

Dates: 2009–2011

Partners: INRIA Saclay-Ile de France (leader of the project), Paris 6, IFP (Rueil-Malmaison), CEA Saclay

Overview: In this collaborative effort, we propose to develop parallel preconditioning techniques for the emergent hierarchical models of clusters of multi-core processors, as used for example in future petascale machines. The preconditioning techniques are based on recent progress obtained in combining the well known incomplete LU (ILU) factorization with the tangential filtering, another incomplete factorization where a filtering condition is satisfied. The goal of this project is to transform these preconditioners into black box parallel preconditioners that could be as usable as standard and popular methods such as ILU. For this, we address several issues related to the quality of the combined preconditioner. We also aim to make the connection of these methods with the domain decomposition methods. To obtain a preconditioner suitable for parallelism, we will study associated graph partitioning and reordering techniques.



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