COMPARISON OF NUMERICAL ANALYSIS OF FLOW PAST TOPOGRAPHY BY TIME-DEPENDENT RANS MODEL AND LES SIMULATION

Abstract

Time-dependent Reynolds-averaged Navier Stokes equation (RANS) and large-eddy simulation (LES) techniques have been applied to the analysis of flow past smooth topography to evaluate the results of both methods. Though RANS method used is a two-dimensional one with two-equation turbulence model, the results reproduce a time dependent large-scale turbulence structure. It appears to be made possible bysufficiently small grid spacing resolving the near-wall laminar sublayer and a small time step, and is something like an LES simulation with filter average taken in the cross stream direction. The overall accuracy of prediction, however, depends on the representation of the laminar-to-turbulent transition and does not appear to have outpassed standard k-ε A method.