A Multigrid Method for Nonconforming FE-Discretisations with Application to Non-Matching Grids

Abstract.Nonconforming finite element discretisations require special care in the construction of the prolongation and restriction in the multigrid process. In this paper, a general scheme is proposed, which guarantees the approximation property. As an example, the technique is applied to the discretisation by non-matching grids (mortar elements).