Assessment of transition modeling for high Reynolds flows

Variants of the eN method and γ–Reθ transition model are thoroughly evaluated against measured data obtained for four airfoils in conditions that range from Re=3 to 40 millions. For the eN method, the option of obtaining the necessary boundary layer thickness properties by integrating the boundary layer equations is compared to that of retrieving this information directly from the flow-field data. It is found that the two options agree when the former uses the Falkner–Skan profiles and the latter utilizes a significantly finer than the baseline grid. Regarding the γ–Reθ model, the effect of inlet conditions and the significance of limiting turbulence production on the accuracy of transition prediction are investigated and found to be important. Regarding the correlation to measurements, in all of the cases considered, even though the two model sometimes agreed qualitatively, the variant of the eN variant that is based on the Falkner–Skan profiles outperformed the γ–Reθ model, especially for Reynolds numbers higher than 5 millions.