Abstract: Four different types of serial multigrid preconditioned conjugate gradient algorithms are applied to treat interface problems, and their numerical convergence rates are also compared with respect to interface types, interface degree and stepsize. Schwarz parallelism is used for algorithms, and discussion concerns the convergence rates with respect to the number of subdomains, and the benefits owing to Schwarz parallelism. Detailed performence results are also given.

Key words: interface problems, multigrid preconditioner, parallel Schwarz relaxations, convergence rate, parallel efficiency