Evaluation of grey area mitigation tools within zonal and non-zonal RANS-LES approaches in flows with pressure induced separation

Hybrid RANS-LES computations of the separated flow over a wall-mounted hump are presented, which employ different grey-area mitigation techniques in the framework of a structured and an unstructured flow solver. Two zonal approaches using different synthetic-turbulence generators at the RANS-LES interface, as well as a non-zonal approach based on a shear-layer-adapted subgrid scale are compared in detail with validation data from a wind-tunnel experiment. Irrespective of the applied flow solver, the different methods are shown to be similarly effective in reducing the grey area compared to the basic hybrid RANS-LES model, and thus provide satisfying mean-flow predictions of the pressure-induced separation. (C) 2017 Elsevier Inc. All rights reserved.