MASSIVELY PARALLEL SIMULATIONS OF ASTROPHYSICAL PLASMAS: STATUS AND PERSPECTIVES OF THE COAST PROJECT B. Thooris, E. Audit, A. S. Brun, Y. Fidaali, F. Masset, D. Pomarède, R. Teyssier Institut de Recherche sur les Lois Fondamentales de l’Univers DSM/IRFU CEA/Saclay 91191 Gif-sur-Yvette France email: Bruno.Thooris@cea.fr http://irfu.cea.fr/Projets/COAST KEYWORDS Large scale computing, parallel computing, astrophysics, plasmas simulation, visualization. ABSTRACT The COAST (for Computational Astrophysics) project is a program of massively parallel numerical simulations in astrophysics involving astrophysicists and software engineers from CEA/IRFU Saclay. The scientific objective is the understanding of the formation of structures in the Universe, including the study of large- scale cosmological structures and galaxy formation, turbulence in interstellar medium, stellar magnetohydrodynamics and protoplanetary systems. The simulations of astrophysical plasmas are performed on massively parallel mainframes (MareNostrum Barcelona, CCRT CEA France), using 3-D magnetohydrodynamics and N-body parallelized codes developed locally. We present in this paper an overview of the software codes and tools developed and some results of such simulations. We also describe the Saclay SDvision graphical interface, implemented in the framework of IDL Object graphics, our 3-D visualization tool for analysis of the computation results. 1. Introduction The COAST project [1,2] is dedicated to high performance computing in astrophysics. The goal is the understanding of the formation of structures in the Universe, by developing advanced techniques in parallel computing and in applied mathematics to model galaxy formation and predict their observational signatures, as a function of physical parameters. Astrophysicists and software engineers collaborate to rationalize and optimize the development of simulation programs by creating a core of common specific modules and using common software tools for data handling, post-treatment, visualization, numerical methods, parallelization and optimization. 2. Overview of the simulation programs Four major numerical simulation programs are used to cover different physics scales: - The RAMSES code RAMSES [3,4,5,6] is a hybrid, N-body and hydrodynamical 3-D code which solves the interplay of the dark matter component and the baryon gas for studying the structure and the distribution of galaxy clusters starting for the initial conditions of the Big Bang. The code is based on the Adaptive Mesh Refinement (AMR) technique, written in FORTRAN90 and parallelized with the MPI library [7]. Current developments focus on solving the full MHD set of equations. - The HERACLES code HERACLES [8,9,10,11,12] is a 3-D code which solves the equations of radiative transfer coupled to hydrodynamics. It studies thermal condensation in molecular clouds in the Interstellar Medium, radiative shocks, molecular jets of young stars and proto-planetary disks. It is written in FORTRAN90, parallelized with MPI and implemented in cartesian, cylindrical and spherical coordinates with regular mesh grids. - The ASH [13,14] code ASH (for Anelastic Spherical Harmonic) performs 3-D magnetohydrodynamics simulations in spherical geometry for the study of the turbulence and magnetic dynamo process in solar and stellar interiors. ASH, unlike the others codes presented which are completely developed in CEA/Saclay, is jointly developed at Saclay and at the University of Boulder. - The JUPITER [15,16,17] code JUPITER is a mutidimensional astrophysical hydrocode. It is based on a Godunov method, written in C and parallelized with MPI. The mesh geometry can either be Proceedings of the 2008 High Performance Computing & Simulation Conference ©ECMS Waleed W. Smari (Ed.) ISBN: 978-0-9553018-7-2 / ISBN: 978-0-9553018-6-5 (CD)