Influence of mesh deformation on the quality of large eddy simulations

Abstract

The influence of mesh motion on the quality of large eddy simulation (LES) was studied in the present article. A three-dimensional, turbulent pipe flow (Reτ=360) was considered as a test case. Simulations with both stretching and static meshes were carried out in order to understand how mesh motion affects the turbulence statistics. The spatial filtering of static and moving mesh direct numerical simulation (DNS) data showed how an ideal LES would perform, while the comparison of DNS cases with static and moving meshes revealed that no significant numerical errors arise from the mesh motion when the simulation is fully resolved. The comparison of the filtered fields of the DNS with a moving mesh with the corresponding LES fields revealed different responses to mesh motion from different numerical approaches. A straightforward test was applied in order to verify that the moving mesh works consistently in LES: when the mesh is stretched in the streamwise direction, the moving mesh results should be in between the two extremal resolutions between which the mesh is stretched. Numerical investigations using four different LES approaches were carried out. In addition to the Smagorinsky model, three implicit LES approaches were used: linear interpolation (non-dissipative), the Gamma limiter (dissipative), and the scale-selective discretisation (slightly dissipative). The results indicate that while the Smagorinsky and the scale-selective discretisation approaches produce results consistent with the resolution of the non-static mesh, the implicit LES with linear interpolation or the Gamma scheme do not. Copyright © 2016 John Wiley & Sons, Ltd.