Large-eddy simulation of separation-reattachment of a flat-plate turbulent boundary layer

We describe large-eddy simulations (LES) of turbulent boundary-layer flow over a flat plate at high Reynolds number in the presence of three-dimensional flow separation. The stretched-vortex subgrid-scale model is used in the bulk of the flow domain combined with a wall-model that is a two-dimensional extension of that described by Chung and Pullin [J. Fluid Mech., 631, 281-309, 2009]. Wall-normal averaging of the wall-parallel, stream-wise momentum equations combined with local inner scaling for the resolved-scale velocity gives an ordinary differential equation describing the wall shear-stress vector at each wall point. Together with a specification of a slip velocity at a raised, wall-parallel plane, this provides a boundary condition for the outer LES that allows local backflow. The present LES is motivated by experiments on flows exhibiting separation induced by the response of a turbulent boundary layer to an adverse-favorable pressure-gradient profile. Detailed discussion of detachment and reattachment of the separation bubble will be presented.