Numerical simulations of astrophysical plasmas

Simulations conducted on high-performance, massively parallel mainframes have become a central tool in the study of astrophysical plasmas. Two parallelized codes, HERACLES and RAMSES, respectively dedicated to the simulation of the interstellar medium dynamics and the formation of cosmological structures, are described. Their algorithms implement a precise modelling of fundamental physical processes, including hydrodynamics, radiative transfer, gravitation, transport, turbulence, and diffusion. These algorithms are developed in Fortran 90 and parallelized with MPI. The RAMSES code benefits from the implementation of the AMR Adaptive Mesh Refinement technique, while the HERACLES code in its current implementation uses fixed, multi-geometrical grids. The technical software aspects of data handling and visualization are discussed. Data management is realized through the use of the HDF5 hierarchical data file format. A graphical interface, developed in the framework of IDL object programming, is presented. This application is optimized to provide interactive, three-dimensional representations of large data sets. Visualization of scalar and vector fields, as well as particles clouds, is obtained for AMR and cartesian grid geometries. Finally, prospects such as the introduction of a multigrid approach to overcome spatial resolution limitations, are presented. Application to other fields are discussed.