Application of gamma-theta transition model to flows around airfoils

The γ-Re_θt̄ transition model which is purely based on local variables and empirical transition correlations is implemented on the nonstructural RANS solver and then is applied to the predictions of flows of low freestream turbulence level around the airfoils of S809 and NLF0416 at moderate and large angles of attack. The computational results indicate that the model can predict various types of transition accurately such as natural transition, separated bubble and relaminarization. Good agreement with the available experimental data such as transition onset locations and lift and drag coefficients was observed in the cases of moderate angles of attack, while the leading edge separated bubble at large angles of attack was predicted as well. The computational results also indicate that the model is sensitive to the streamwise thickness of computational grid on the wall boundary and to the discretization scheme of the convective terms.