Behavior of Detached-Eddy Simulations for Mild Airfoil Trailing-Edge Separation

The flow around the A-airfoil at the maximum lift condition (alpha = 13.3 degrees) with a chord Reynolds number of 2 x 10(6) is simulated using unsteady Reynolds-averaged Navier-Stokes solution, detached-eddy simulation, and delayed- detached eddy simulation. This case features a relatively thick boundary layer with a mild trailing-edge separation. Detailed comparisons of the modeled Reynolds stresses are carried out with the available experimental data at different locations on the suction side of the airfoil and in the wake region. The impact of the delayed switching on modeled Reynolds stresses from delayed-detached-eddy simulation as compared with the original detached-eddy simulation is studied. On the suction side of the airfoil, the modeled turbulent Reynolds stresses computed through the detached-eddy simulation are generally lower than the unsteady Reynolds-averaged Navier-Stokes solutions, whereas the delayed-detached-eddy simulation gives comparable values with the unsteady Reynolds-averaged Navier-Stokes solutions results. None of them give consistent comparison with the experimental Reynolds stresses. It is observed that for the cases with the mild separation, the original detached-eddy simulation may perform better than the delayed-detached-eddy simulation, due to its relatively lower turbulent dissipation levels. The detached-eddy simulation Reynolds stresses in the wake region show better results, in comparison with the experimental data.