A surface-resolved unstructured method for large-scale simulation of particle-laden turbulent flow*

Particle-laden flows involve a large range of length scales spanning from large convective scales down to scales near that of individual particles. Resolving the fluid features below that of individual particles presents difficult numerical challenges. We present a method that simulates such cases for many moving particles (O (100,000) particles) using surface-resolved unstructured overset meshes. A dynamic overset assembly is conducted to connect mesh solutions. To establish communication patterns a parallel master/slave algorithm is used. A parallel flood-fill algorithm is used for cutting. For searches, k-d tree data structures are used. Often the connectivity between overset meshes remains the same between time steps. The temporal coherence of objects is directly used to only update necessary information with time, resulting in substantial cost savings. A non-dissipative method is used for the fluid flow. An interpolant is used which has superior kinetic energy properties compared to local reconstructions. To solve pressure, a penalty constraint formulation is used, resulting in a symmetric, positive definite system. Canonical flows are shown. Strong scaling is demonstrated for 100,000 particles in a turbulent channel flow up to 492,000 cores.