The Lattice Boltzmann Method Implemented on the GPU to Simulate the Turbulent Flow Over a Square Cylinder Confined in a Channel

Abstract

The lattice Boltzmann method (LBM) is a relatively new method for fluid flow simulations, and is recently gaining popularity due to its simple algorithm and parallel scalability. Although the method has been successfully applied to a wide range of flow physics, its capabilities in simulating turbulent flow is still under-validated. Hence, in this paper, a 3D LBM code was developed to investigate the validity of the LBM for turbulent flow simulations through large eddy simulations (LES). A GPU enabled LBM code was developed, and validated against a benchmark test case involving the flow over a square cylinder in square channel. The flow results showed good agreement with literature, and speedups of over 150 times were observed when two GPUs were used in parallel. Turbulent flow simulations were then conducted using LES with the Smagorinsky subgrid model. The methodology was first validated by computing the fully developed turbulent channel flow, and comparing the results against direct numerical simulation results. The results were in good agreement despite the relatively coarse grid. The code was then used to simulate the turbulent flow over a square cylinder confined in a channel. In order to emulate a realistic inflow at the channel inlet, an auxiliary simulation consisting of a fully developed turbulent channel flow was run in conjunction, and its velocity profile was used to enforce the inlet boundary condition for the cylinder flow simulation. Comparison of the results with experimental and numerical results revealed that the presence of the turbulent flow structures at the inlet can significantly influence the resulting flow field around the cylinder.