Multigrid computation for turbulent recirculating flows in complex geometries

Computation of recirculating turbulent flow in complex geometries is important in engineering but fundamentally difficult. A procedure using a full multi-grid and full approximation storage is developed in conjunction with a pressure-based algorithm using curvilinear coordinates and the k-ϵ two-equation turbulence model. This method is applied to several flow problems with different geometries, grid sizes, and convection schemes. Although the multi-grid procedure does not yield a convergence rate independent of these factors, its performance is noticeably less affected than that of the single-grid method. Degradation of the boundary representation during grid restriction is one effect on the multigrid performance. Some features regarding the treatment of the turbulence quantities that help the performance of the multigrid method are identified. A special grid restriction procedure is also introduced, which accommodates the velocity characteristics in the wall region and kelps improve the convergence rate.