LES AND URANS UNSTEADY BOUNDARY LAYER STRATEGIES FOR PULSATING AND OSCILLATING TURBULENT CHANNEL FLOW APPLICATIONS.

Abstract. The use of wall functions has been investigated for LES and URANS numeri-cal 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 discrepancy 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 un-steady flow effect, the boundary layer needs to be resolved. Different approach 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 backdraw is unfortunately the increasing of computational points in the boundary layer and consequently the higher computational cost. 1