Analysis of Resolved Turbulent Scales of Motion in Aeroelastic Problems

摘要

Flow conditions in Test Case 3 in the second AIAA Aeroelastic Prediction Workshop are such that the boundary layer separates downstream of shock waves on the upper and lower wind sides, generating large scale turbulence. As a consequence, the separation between mean flow and turbulent lenghtscales may not be sufficiently large to make the URANS approach accurate and physically consistent. Hybrid RANS-LES models are a logical option to the URANS approach. However, these models require a higher spatial resolution in the regions of separated flow and a much finer temporal resolution. This study focuses on Test Case 3, which has been calculated with a twofold objective: firstly presenting the results obtained with DLR-Tau following the URANS approach and, secondly, investigate the consistency of the turbulent spectrum resolved by DDES calculations, in this work carried out with the solver SU2, of which a secondary development branch is available, with implementation of the SA-DDES model along with two major improvements aimed at reducing the so-called gray area, i.e. the interface between RANS and LES. This work shows that both approaches can resolve the largest turbulent structures but that only the hybrid approach can provide a physically meaningful solution, as long as sufficient spatial and temporal resolutions are available.