Characterization of Off-Surface Separation Caused by Adverse Pressure Gradient in a Turbulent Wake

Abstract

The present contribution focuses on the behavior of two RANS Reynolds stress turbulence models in the prediction of off-surface separation occurring in turbulent wakes subjected to strong adverse pressure gradients. RANS results are compared to a high-fidelity RANS-IDDES solution for an experimental set-up from Driver and Mateer. The tested models are the JHh-v2 and the SSG/LRR. Additionally, the comparison includes a modified version of the SSG/LRR model where the sensitivity to pressure gradients is enhanced by the S-eps-4 term, which is already present in the JHh model. None of these RANS approaches was able to capture the off-surface recirculation as shown by the IDDES. The analysis aims at characterizing the wake flow and identifying possible sources of the RANS shortcomings, such as departure from dynamic equilibrium and strong Reynolds stress anisotropy