Towards Large-eddy Simulation of Turbulent Flows with Complex Geometric Boundaries Using Immersed Boundary Method

Abstract

Approximate immersed boundary conditions for large-eddy simulation (LES) of turbulent flows in combination with immersed boundary method are proposed. The approximate immersed boundary conditions are based on the fluxes and the shear stresses in order to ensure the momentum conservation: the velocity boundary conditions are imposed to the convection terms and the shear stress boundary conditions imposed to the diffusion terms. On a body-fitted grid, they are exactly the same as the non-penetration and wall stress boundary conditions, for the immersed boundary method they are now the generalized off-wall boundary conditions. This strategy is tested in turbulent channel flows with the wall not being aligned with Cartesian grids. The results obtained show the promising of this strategy in simulations of high Reynolds number turbulent flows. The effects of different eddy-viscosity models used in conjunction with approximate immersed boundary conditions need to be further investigated.