LES and URANS Unsteady Boundary Layer Strategies for Pulsating and Oscillating Turbulent Channel Flows Applications

Abstract

The use of wall functions has been investigated for LES and URANS numerical simulation in pulsating and oscillating channel flow applications. The results show that the wall function approach is accurate in the so-called quasi-steady regime but there are discrepancies with the experimental results in the intermediate frequency range. A special attention is given to the wall-shear stress prediction, and in particular on the wall-shear stress phase shift with respect to the free stream velocity. In order to capture such unsteady flow effects, the boundary layer needs to be resolved. Different approaches such as Low Reynolds Number near wall turbulence modeling (URANS) or the proposed Wall-Normal Resolved strategy (LES) seem to be suited for this purpose. The drawback is unfortunately the increasing of computational points in the boundary layer and consequently the higher computational costs.