A Scalable Parallel Unstructured Finite Volume Lattice Boltzmann Method For Three-Dimensional Incompressible Flow Simulations

The standard lattice Boltzmann method, which employs certain regular lattices coupled with discrete velocities as the computational grid, is limited in its flexibility to simulate flows in irregular geometries. To simulate large-scale complex flows, we present a cell-centered finite volume lattice Boltzmann method for incompressible flows on three-dimensional (3D) unstructured grids and its corresponding parallel algorithm. The advective fluxes are calculated by the low-diffusion Roe scheme, and the gradients of the particle distribution functions are computed with a least squares method. The presented scheme is validated by three benchmark flows: (a) a 3D Poiseuille flow, (b) cubic cavity flows with Reynolds numbers Re = 100 and 400, and (c) flows past a sphere with Re = 50, 100, 150, 200, and 250. Some parallel performance results are presented to show the scalability of the method, which reveal that the proposed parallel algorithm has considerable scalability and that the parallel efficiency is higher than 87% on 3840 processor cores. It can be seen that the presented parallel solver has significant potential for the accurate simulation of flows in complex 3D geometries.