waLBerla, an ultra-scalable multi-physics simulation framework for piecewise regular grids
Christian Godenschwager, Universität Erlangen-Nürnberg
waLBerla is a massively parallel software framework for the simulation of complex multi-physics processes. While, in the past, the main focus has been on flow simulations with the lattice Boltzmann
method, waLBerla has recently been extended to support simulations of ternary eutectic solidification processes using a thermodynamically consistent phase-field method. We will show performance measurements for both LBM and phase-field simulations on the three German tier-0-systems JUQUEEN, SuperMUC, and Hermit. We demonstrate excellent scalability on all three machines using up to 1.8 million threads on JUQUEEN. Beyond scalability, we present an outstanding single-node performance which is achieved by a careful performance engineering process. Elaborate node level optimizations, vectorization using SIMD instructions, and fully distributed data structures allow for exploiting the full potential of current and upcoming supercomputers.