The numerical solution of flow problems with multigrid techniques is considered. The use of extra iterations on coarser grids is investigated. The two-grid method is analyzed for model problems. It turns out that the optimum number of iterations depends on the mesh size of the fine grid.
Numerical examples verify the results.
A short discussion on more grid levels is also given. The results are applicable for problems with open boundaries. 65N55, 76N10 PII .