HLPW-4/GMGW-3: Hybrid RANS/LES Technology Focus Group Workshop Summary

Abstract

This paper summarizes the collective efforts of multiple teams in the hybrid RANS/LES technical focus group and the resulting presentations that were made at the 4th AIAA CFD High Lift Prediction Workshop (HLPW-4), that took place virtually, and in person, on January 7, 2022, in San Diego, California. The overall conclusion is that for these high-lift devices, turbulence-resolving methods such as hybrid RANS/LES (HRLES) methods do seem to offer improved predictions with respect to the underlying RANS models, but there are nuances and some unresolved issues remaining that should be the focus of future work. In particular, while HRLES methods appear to show clearly improved predictions at higher angles of attack, at lower angles of attack there is some tendency for hybrid methods to return slightly worse moment predictions, suggesting that prediction of the shallow separation from the flaps might need further research. Computing cost also remains a significant issue, with HRLES methods requiring roughly 10-15 times more HPC core-hours than steady-state RANS methods, indicating that future algorithmic and computational optimization could be beneficial. Finally, there are strong indications that modeling the wind-tunnel has a positive impact on correlation with experimental measurements, suggesting that future work might be better focused on in-tunnel simulations.