Grid-Adapted FUN3D Computations for the Second High-Lift Prediction Workshop

Abstract

Contributions of the unstructured Reynolds-averaged Navier–Stokes code FUN3D to the 2nd AIAA Computational Fluid Dynamics High-Lift Prediction Workshop are described, and detailed comparisons are made with experimental data. Using workshop-supplied grids, FUN3D results for the simplified high-lift configuration are compared with results from the structured code CFL3D. Using the same turbulence model, both codes compare reasonably well in terms of total forces and moment, and the maximum lift is similarly over-predicted for both codes compared to experiment. By including more representative geometry features such as slat and flap support brackets and slat pressure tube bundles, FUN3D captures the general effects of the Reynolds number variation, but under-predicts maximum lift on workshop-supplied grids in comparison with the experimental data due to excessive separation. However, when output-based, off-body grid adaptation in FUN3D is employed, results improve considerably. In particular, when the geometry includes both brackets and the pressure tube bundles, grid adaptation results in a more accurate prediction of lift near stall in comparison with the wind-tunnel data. Furthermore, a rotation-corrected turbulence model shows improved pressure predictions on the outboard span when using adapted grids.