Simulation of high Reynolds number flow over a backward facing step using SPH

Abstract

The flow over a backward facing step is often used as a test case for analyzing the performance of computational methods and turbulence models. It embodies several important aspects of turbulent flow: flow separation, recirculation, and reattachment. It is convenient that the separation point is fixed at the sharp corner of the step, so no complexities arise from movement of the separation point. We report on high Reynolds number simulations of flow over a backward-facing step using the Lagrangian Smoothed Particle Hydrodynamics (sph) method. A preliminary attempt to quantitatively evaluate the ability of sph to predict high Reynolds number flows is made here. The effect of using a sub-particle scale model within sph similar in concept to a subgrid scale model in grid-based Large Eddy Simulations is investigated. Simulations were performed at three different sph resolutions and compared with experimentally and numerically (using traditional grid based cfd) observed velocity profiles and the re-attachment length. The flow Reynolds number was 132,000 based on the inlet velocity and the downstream channel height.