Wall modeling in complex geometry and application to large-eddy simulation of turbulent flow over an airfoil

Resolving the energy-containing eddies near the wall in high Reynolds number wall-bounded turbulent flows requires grid sizes of order O(Re13/7). Wall-modeled large-eddy simulation (WMLES) leads to a relaxation of this resolution constraint. The proposed wall model predicts the the velocity components on a “virtual wall” located at some distance above the solid wall rather than resolving the near-wall region. The wall-modeling approach appears to a tenable solution for LES of high-Re wall-bounded turbulent flows. In this work, we develop a generalized wall model for complex geometry of relevance to engineering applications such as aircraft and wind turbines. The virtual wall model, originally developed by Chung & Pullin (J. Fluid Mech., 2009), is extended to the curvilinear coordinates and implemented for a body-fitted structured mesh. This model dynamically couples the outer resolved region with the wall region, and offers a slip velocity boundary condition for the filtered velocity field on the virtual wall. The wall-model is verified by comparing our WMLES results of NACA airfoil cases at different Re against direct numerical simulation. Numerical results indicate that the current model is effective in predicting separation.