Performance-Portable Multiphase Flow Solutions with Discontinuous Galerkin Methods

We present a performance portable solver workflow for developing multiphase flow simulations based on the OP2 domain-specific language. The workflow brings together the state-of-the-art in multiphase flow solutions and uses discontinuous Galerkin (DG) methods for achieving high-order accuracy within OP2’s established performance portable framework. A key aspect of the modelling is managing the fluid interface through high-order methods while maintaining stability, accuracy and performance. The new OP2-DG methods are used for developing the non-trivial multiphase liquid whistle problem, 4M to 128M element meshes / 80M to 2.4B degrees of freedom, representative of an application used in formulated products manufacturing. The OP2-generated code is benchmarked on an AMD EPYC CPU-based HPE-Cray EX cluster, a NVIDIA V100 GPU cluster and an AMD MI250X GPU cluster. The runtime and scaling performance is analysed, demonstrating how superior high-order solutions can be achieved without sacrificing performance portability while approaching tractable times-to-solution for large multiphase flow simulations that were previously out of reach.