A dynamic stochastic forcing method as a wall-layer model for large-eddy simulation

Abstract

Turbulence-resolving simulations of wall-bounded flows at high Reynolds numbers are presently unattainable due to the need to resolve fully the energy-carrying eddies in the near-wall region. Hybrid Reynolds-averaged Navier–Stokes/large-eddy simulations (RANS/LES), in which the near-wall eddies are modelled in a Reynolds-averaged sense, provide a cost-saving alternative. However previous attempts at combining a RANS near-wall layer with a LES outer flow have resulted in a large transition region which causes a shift in the mean velocity profile and low values of the skin friction coefficient. The present work presents a dynamic stochastic forcing method, that, when coupled with the detached-eddy simulation methodology, significantly speeds up this transition resulting in more accurate predictions of the mean velocity profile as well as the velocity fluctuations. The method is shown to be equally effective in a periodic and in a spatially developing flow.