Validation of flow around NREL S809 airfoil using Gamma 3 equation and Gamma-ReTheta 4 equation transition model

In this study, we analyzed the flow around the NREL S809 airfoil using STAR-CCM+ with the γ 3-equation and γ-Reθ 4-equation transition models. The effect of spatial mesh resolution was investigated, and it was found that the pressure coefficient distributions from both models converged numerically when the resolution was Super Fine or higher. The effect of boundary layer mesh resolution was also examined. For both transition models, the number of prism layers had little influence on the pressure coefficient, but the lift coefficient exhibited numerical oscillations as the number of layers was reduced. Comparison with experiments showed that both models were capable of capturing transition behavior with sufficient accuracy, provided that both the spatial resolution and the number of boundary layers were sufficient. The γ-Reθ 4-equation transition model showed better agreement with the experimental results.