Parallel Computations of High-Lift Airfoil Flows Using Two-Equation Turbulence Models

Abstract

Viscous turbulent ows over high-lift airfoils are investigated by using unsteady, incompressible, and compressible Reynolds-averaged Navier– Stokes equations under a parallel computing environment. Compressibility effects can be signi cant in the leading-edge region of high-lift airfoils with a highly loaded element. Thus, both the incompressible and compressible computations are performed to study the compressibility effects. The compressible code involves an upwind-differenced scheme for the convective terms and a lower– upper symmetric Gauss– Seidel scheme for temporal integration. The incompressible code with a pseudocompressibility method also adopts the same schemes as the compressible code. Both codes are parallel processed by using message passing interface programming method and show good parallel speedups. Three two-equation turbulence models (the standard k–ε, the k–ω, and the k–ω shear stress transport model) are carefully evaluated by computing the ows over single-element and multielement airfoils. The compressible and incompressible codes are validated by predicting the ow around 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 ow over the NLR 7301 airfoil with ap and the NASA GAW-1 high-lift airfoil. Compressibility effects on surface pressure coef cients, velocity pro les, and skin friction coef cients are numerically simulated.