A multigrid method or the mortar-type Morley element approximation of a plate bending problem

In this paper, a multigrid algorithm is presented for the mortar element method for the Morley nonconforming plate element. Based on the multigrid theory developed by Bramble, Pasciak, and Xu in [ Math. Comp., 56 (1991), pp. 1-34], we prove that the W-cycle multigrid method is optimal, i.e., the convergence rate is independent of the mesh size and mesh level. Moreover, a variable V-cycle multigrid preconditioner is constructed, which results in a preconditioned system with a uniformly bounded condition number.