Enabling Tools and Techniques for the Optimization of the HERACLES Simulation Program

Simulations conducted on high-performance, massively parallel mainframes have become a central tool in the study of astrophysical plasmas. HERACLES is a radiation hydrodynamics program used in particular to investigate turbulences in interstellar molecular clouds. In the framework of the COAST engineering project conducted at Saclay, a special effort has been undertaken to provide enabling tools and techniques for the HERACLES program, including the development of a multiple-grid approach to overcome spatial resolution limitations, optimization and parallelization methods, data handling facilities and visualization tools. COAST (for Computational Astrophysics) is a CEA/DAPNIA project dedicated to high performance computing in astrophysics. The originality of the project is the collaborative work of astrophysicists and software engineers with the aim to develop common tools and techniques for different independent astrophysical simulation programs. In particular, the techniques of multiple-grid and interlocked meshes are being developed in the finite volumes HERACLES program; these developments rely on parallelized algorithms for which optimization is pursued. The SDvision graphical interface, implemented in the framework of IDL object programming, is also presented, as the visualization tool for analysis of the computation results