An Analysis of Modeling Sensitivity Effects for High Lift Predictions using the Flow 360 CFD Solver

This paper presents the contribution of Flexcompute to the 4th High Lift PredictionWorkshop based on the Flow360 solver. The analysis of the high-lift prediction results is focused on four key areas: mesh sensitivity, turbulence modelling sensitivity, effect of cold- vs warm-starts and an examination of hysteresis effects. The mesh sensitivity study includes the use of different mesh topologies, families and levels of mesh refinement for the committee and non-committee provided grids. Through the analysis of the resolution of the different flow features recommendations are put forward regarding meshing for future workshops. Next, results are presented using different RANS-based turbulence models, with a focus on the eddy viscosity levels in the flow structures and separated flow predictions. Following, a detailed analysis is performed for comparing cold-starts versus warm-starts with a focus on comparing the differences in the skin friction and flow fields at each angle of attack. Hysteresis effects are also examined to establish the effect of the initial condition on the solution. Finally, the best practice RANS results are analyzed in detail along with DES simulations with the aim to provide conclusions of the ability of RANS to predict high lift flows. The DES results were found to significantly improve the comparison with experimental data and showed high confidence in terms of achieving the correct answer for the right reasons.