Parallel computations of high-lift airfoil flows using two-equation turbulence models

Viscous turbulent flows over high-lift airfoils are investigated by using u nsteady, incompressible, and compressible Reynolds-averaged Navier-Stokes e quations under a parallel computing environment. Compressibility effects ca n be significant in the leading-edge region of high-lift airfoils with a hi ghly loaded element. Thus, both the Incompressible and compressible computa tions are performed to study the compressibility effects. The compressible code involves an upwind-differenced scheme for the convective terms and a l ower-upper symmetric Gauss-Seidel scheme for temporal integration. The inco mpressible code with a pseudocompressibility method also adopts the same sc hemes as the compressible code. Both codes are parallel processed by using message passing interface programming method and show good parallel speedup s. Three two equation turbulence models (the standard k-epsilon, the k-omeg a, and the k-omega shear stress transport model) are carefully evaluated by computing the flows over single-element and multielement airfoils. The com pressible and incompressible codes are validated by predicting the flow aro und the RAE 2822 transonic airfoil and NACA 4412 airfoil, respectively. In addition, both the incompressible and compressible codes using the Chimera overlapping grid scheme are used to compute the how over the NLR 7301 airfo il with Rap and the NASA GAW-1 high-lift airfoil. Compressibility effects o n surface pressure coefficients, velocity profiles, and skin friction coeff icients are numerically simulated.