UNSTEADY SIMULATIONS OF MASSIVELY SEPARATED FLOW AROUND NACA0021 AIRFOIL USING A TRANSITIONAL IDDES MODEL

A blended IDDES and correlation-based transition model, named as the γ-IDDES model, has been newly added in OpenFOAM v2106 to simulate the massively separated flow around NACA0021 airfoil at the angles of attack (AoAs) from 30° to 90°. Compared to the fully turbulent SST-IDDES model and the γ-SST RANS model, the γ-IDDES model can give the best predictions on the lift and drag coefficients at all the AoAs. At the AoAs of 30° and 40°, both the γ-IDDES model and the γ-SST RANS model can perform a little better than the SST-IDDES model on the predictions of lift and drag coefficients. This hints that the boundary layer transition may play a notable role in the simulation of massively separated flow by the subsequent flow analysis. When the AoAs are larger than 50°, both the γ-IDDES model and the SST-IDDES model can give accurate predictions on the lift and drag coefficients. In contrast, the γ-SST RANS model fails in the prediction of lift and drag coefficients. This illustrates that the capacity of capturing the flow structures is still essential in the simulation of massively separated flow.