Intergrid Transfer Operator for Multigrid of Mortar-type Rotated Q_1 Element

In this paper,we study the convergence of multigrid algorithm for mortar-type rotated Q1 element.For nonnested rotated Q1 finite element spaces,we present two mortar conditions and propose a kind of intergrid transfer operator for multigrid algorithm for mortar rotated Q1 element,meanwhile,we establish a corresponding criterion for the intergrid transfer operator,i.e.,the multigrid algorithm converges optimally,if the intergrid transfer operator satisfies the criterion.The theoretical and numerical simulations show the convergence of the multigrid algorithm.