On simulating the flow past a normal thin flat plate

Abstract

Initially, the uniform flow past a normal two-dimensional flat plate of zero-thickness was studied using Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) at Reynolds number of 1200. An extensive review of previous numerical and experimental studies on the wake of flat plates highlights important discrepancies, which are reconciled by the present detailed sensitivity study of domain, boundary conditions and turbulence modeling specifications. It is shown that differences in important flow features, such as the mean recirculation length, drag and pressure distributions are related to the strong Re−effects for Re<1000. Detailed comparison of DNS and LES studies at Re=1200 with measurements up to Re=1.5×105 suggest that for Re>1000, the influence of the Reynolds number is small. Moreover, it is found that some important differences in the LES and DNS simulations, despite similar grid resolution, can be related to specific behavior of the Sub-Grid Scale Smagorinsky model in regions of high anisotropy and adverse pressure gradient in the recirculation zone even at high Re. Finally, it is observed that the pressure distribution on the windward surface of the plate is highly sensitive to the wake flow, which helps explain discrepancies between experimental and numerical studies in terms of an unusual sensitivity to the experimental conditions.