High-Lift Prediction Workshop 5: Hybrid RANS/LES Technology Focus Group Summary

This study summarizes the work of the hybrid Reynolds-averaged Navier-Stokes/large-eddy simulation (HRLES) Technology Focus Group (TFG) for the 5th High-Lift Prediction Workshop (HLPW-5). Results indicate that, as shown in HLPW-4, HRLES methodologies continue to consistently outperform Spalart–Allmaras-based RANS models in predicting maximum lift coefficients ([Formula: see text]) and flowfield correlations for a range of high-lift aircraft geometry variations—from clean wings to those with flaps, slats, and engine nacelles. However, challenges persist in simulating low angle-of-attack configurations with deployed flaps, as well as the transitional flow in some of the lower-Reynolds-number cases studied. This work also highlights the importance of mesh resolution in achieving consistent results across different HRLES implementations. For test case 2.2, including deployed slats, lift-convergence trends indicate that meshes with at least approximately 175 million cells were needed to approach an asymptotic region; comparable convergence could not be demonstrated for all configurations and angles of attack. Code-to-code agreement was strongest for adequately resolved Spalart–Allmaras-delayed detached-eddy simulation-family submissions away from stall conditions. A single cost ratio relative to RANS could not be inferred from the workshop submissions, although representative HRLES calculations required tens of convective time units before collecting stationary statistics. While HRLES methods demonstrate promise for industrial applications, this work underscores the need for further research to enhance the maturity and widespread applicability of these methods.