Wall-modeled large eddy simulation of laminar and turbulent separated flows

The capability of the recently proposed integral wall model for large eddy simulation (iWMLES) to capture flow separation, transition, and reattachment is investigated by means of flow over a flat plate with a suction and blowing boundary condition. Wall-resolving LES can accurately recover time-averaged DNS results for a laminar separation bubble, but are limited to moderate Reynolds numbers due to the strong requirement of resolving the boundary layer. Typical equilibrium wall-models do not take pressure gradients into account, and many hybrid RANS-LES either rely on the equilibrium assumption or require very fine mesh spacing in the wall-normal direction. iWMLES addresses these deficiencies through the addition of non-equilibrium terms in an integral version of the momentum equation. iWMLES of a laminar separation bubble flow confirm that the wall-model can capture flow separation, transition, and reattachment at Re_δ = 10⁵ on a coarse grid. Good qualitative agreement with a wall-resolved LES of a turbulent separation bubble is obtained using iWMLES on a coarser wall-normal grid. Trends in both mean and RMS velocities as well as the coefficient of pressure are well predicted by the iWMLES.