MULTIGRID ALGORITHMS FOR NONCONFORMING AND MIXED METHODS FOR NONSYMMETRIC AND INDEFINITE PROBLEMS

In this paper we consider multigrid algorithms for nonconforming and m ixed finite element methods for nonsymmetric and/or indefinite ellipti c problems. We show that a simple V-cycle multigrid iteration using co nforming coarse-grid corrections converges at a uniform rate provided that the coarsest level in the multilevel iteration is sufficiently fi ne (but independent of the number of multigrid levels). Various types of smoothers for the nonsymmetric and indefinite problems are discusse d. Extensive numerical results are presented.