Zonal embedded grids for numerical simulations of wall-bounded turbulent flows

A B-spline based numerical method on a zonal embedded grid has been developed. The method is aimed at reducing the computational requirements for large eddy simulations (LES) and direct numerical simulations (DNS) of wall-bounded turbulent flows. The objective is to reduce the number of grid points required to resolve the near-wall eddies without placing a large number of grid points in the outer layers. DNS and LES calculations of a turbulent channel flow were performed on a grid with a zone near the wall that was refined in all three directions. The results from the zonal grid calculations show good agreement with previously published numerical and experimental results obtained for the same flow conditions. The zonal grid calculations required only a fraction of the CPU time required for the single zone grid calculation with the same near-wall grid density. in addition, the memory requirements for the zonal grid calculations are significantly reduced. (C) 1996 Academic Press, Inc.