Immersed boundary based near-wall modeling for large eddy simulation of turbulent wall-bounded flow

Abstract

This paper describes the coupling of the immersed boundary method and the near-wall modeling of large eddy simulation for high Reynolds number turbulent flows over complex geometries on Cartesian grids. To overcome the spurious oscillation problem arising from the imposition of boundary conditions on the stair-case off-wall boundaries, several key ingredients have been employed, such as interpolating the friction velocity instead of the flow velocity from near-wall fluid interior points, evaluating the gradients by the weighted least square method and correcting the wall-normal gradient of the tangential velocity with the law of the wall at the off-wall boundaries. Furthermore, a hybrid RANS-LES approach has been applied to the near-wall eddy viscosity, either through an empirical blending function or the Reynolds stress balance constraint. We systematically discuss the effects of the hybrid eddy viscosity in a turbulent channel flow and a high lift three-element airfoil. Enforcing the Reynolds stress balance constraint turns out to be very robust in the considered cases. For the high lift three-element airfoil flow, the overall wall pressure and skin friction are predicted reasonably well and smoothly. The flow details are in a good agreement with the experimental data as well.