Turbulence modeling of deep dynamic stall at relatively low Reynolds number

This paper investigates numerically the unsteady separated turbulent flows around an oscillating airfoil pitching in a sinusoidal pattern that induces deep dynamic stalls. The flow is in the regime of relatively low Reynolds number of the order of 105 based on the chord length of the airfoil. Both the URANS and the more advanced DES approaches are employed. The URANS is coupled with two advanced turbulence models, namely the RNG k−ε model and the Transition SST model (γ−Reθ model) and the DES is coupled with the SST k−ω model. A comparison with experimental data shows that the SST k−ω based DES approach is superior to the URANS approach and presents generally good agreement with the experimental data, although the prediction of experimentally observed peek stall angle of attack may not be warranted. The details of the complex flow development of the dynamic stall and the boundary layer transition have been discussed.