No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

SUMMARYAn unstructured non-nested multigrid method is presented for e cient simulation of unsteady incompressible Navier-Stokes ows. The Navier-Stokes solver is based on the artiÿcial compressibility approach and a higher-order characteristics-based ÿnite-volume scheme on unstructured grids. Unsteady ow is calculated with an implicit dual time stepping scheme. For e cient computation of unsteady viscous ows over complex geometries, an unstructured multigrid method is developed to speed up the convergence rate of the dual time stepping calculation. The multigrid method is used to simulate the steady and unsteady incompressible viscous ows over a circular cylinder for validation and performance evaluation purposes. It is found that the multigrid method with three levels of grids results in a 75% reduction in CPU time for the steady ow calculation and 55% reduction for the unsteady ow calculation, compared with its single grid counterparts. The results obtained are compared with numerical solutions obtained by other researchers as well as experimental measurements wherever available and good agreements are obtained.

No abstract