Balancing Destruction and Production in S-A Model-Based Hybrid RANS-LES for Flow around an Aerofoil with Mild Separation

Abstract

The flow around the Aerospatiale A-airfoil at the maximum lift condition with a chord Reynolds number of 2.0×106 is simulated using Unsteady Reynolds-Averaged Navier-Stocks Simulation (URANS), Detached Eddy Simulation (DES), Delayed DES (DDES) and a new approach. The new approach (named WAD-DES) is based on the Spalart-Allmaras (S-A) model and has a weighted average of destruction terms from the Smagorinksy model and the S-A model. The aim of this study is to investigate the behaviour of the S-A-based model working as a sub-grid scale (SGS) model in simulating mild trailing edge separation. The results show that in the near-wall region WAD-DES is better than DES and comparable to DDES. In the wake region, WAD-DES provides the closest velocity profiles to those from the experimental data, due to a reduced level of modelled turbulent viscosity. It is shown that this new WAD-DES approach inherits the advantages of DDES in simulating shallow separation, and also increases the accuracy of prediction in regions further away from the wall.