DES, Hybrid RANS/LES and PANS Models for Unsteady Separated Turbulent Flow Simulations

This paper presents computational results for two DES (Detached Eddy Simulation), one hybrid RANS (Reynolds Averaged Navier-Stokes)/ LES (Large Eddy Simulation) and some preliminary results from PANS (Partially Averaged Navier-Stokes) turbulence for simulation of unsteady separated turbulent flows. The models are implemented in a full 3-D Navier Stokes solver and are based on the two-equation k-ε model. The formulations of each model are presented and results are analyzed for subsonic flow over a Backward Facing Step (BFS). Simulations are carried out using a 3^rd order Roe scheme. A comparative assessment is made between the predictions from the DES, hybrid and PANS models. The predicted results are compared with the available experimental data for skin-friction coefficient, and different turbulent quantities. The three-dimensionality of the flow field and the separated fine scale structures are presented through the Q iso-surfaces.