A mixed overset grid/immersed boundary approach for CFD simulations of complex geometries

A methodology to mix Chimera and Immersed Boundary approaches in the same CFD computation is presented in order to deal with complex geometries. Where accuracy is required in a vicinity of an obstacle, a body-fitted mesh is used to accurately simulate the boundary layer. Otherwise, an immersed boundary method (IBM) is applied to deal with this obstacle. Each body-fitted mesh is generated independently in an overset grid fashion. A set of Cartesian grids that are adapted to the spatial resolution of body-fitted grids and immersed boundaries is generated automatically and overlaps the body-fitted grids. In this paper, we describe the overall procedure to mix the overset grid and immersed boundary approaches, then we detail how the present IBM enables to deal with geometrically complex configurations. Finally, preliminary results of the simulation of a turbulent flow past two cylinders in tandem are presented.