Optimisation of Code_Saturne for Petascale Simulations

Some of the optimisations required to prepare Code_Saturne for petascale simulations are presented in this white paper, along with the performance of the code. A mesh multiplication package based on parallel global refinement of hexahedral meshes has been developed for Code_Saturne to handle meshes containing billions† of cells and to efficiently exploit PRACE Tier-0 system capabilities. Several parallel partitioning tools have been tested and Code_Saturne performance has been assessed up to a 3.2 billion cell mesh. The parallel code is highly scalable and demonstrates good parallel speed-up at very high core counts, e.g. from 32,768 to 65,536 cores