Direct Numerical Simulation and Large Eddy Simulation on a Turbulent Wall-Bounded Flow Using Lattice Boltzmann Method and Multiple GPUs

Abstract

Direct numerical simulation (DNS) and large eddy simulation (LES) were performed on the wall-bounded flow atReτ=180using lattice Boltzmann method (LBM) and multiple GPUs (Graphic Processing Units). In the DNS, 8 K20M GPUs were adopted. The maximum number of meshes is6.7×107, which results in the nondimensional mesh size ofΔ+=1.41for the whole solution domain. It took 24 hours for GPU-LBM solver to simulate3×106LBM steps. The aspect ratio of resolution domain was tested to obtain accurate results for DNS. As a result, both the mean velocity and turbulent variables, such as Reynolds stress and velocity fluctuations, perfectly agree with the results of Kim et al. (1987) when the aspect ratios in streamwise and spanwise directions are 8 and 2, respectively. As for the LES, the local grid refinement technique was tested and then used. Using1.76×106grids and Smagorinsky constant(Cs)=0.13, good results were obtained. The ability and validity of LBM on simulating turbulent flow were verified.