This work was supported in part by NSF grant numbers DMS-0410030 and DMS-0311902.
Algorithms, Equations -- Numerical solutions, Laplacian operator
We investigate some simple finite element discretizations for the axisymmetric Laplace equation and the azimuthal component of the axisymmetric Maxwell equations as well as multigrid algorithms for these discretizations. Our analysis is targeted at simple model problems and our main result is that the standard V-cycle with point smoothing converges at a rate independent of the number of unknowns. This is contrary to suggestions in the existing literature that line relaxations and semicoarsening are needed in multigrid algorithms to overcome difficulties caused by the singularities in the axisymmetric Maxwell problems. Our multigrid analysis proceeds by applying the well known regularity based multigrid theory. In order to apply this theory, we prove regularity results for the axisymmetric Laplace and Maxwell equations in certain weighted Sobolev spaces. These, together with some new finite element error estimates in certain weighted Sobolev norms, are the main ingredients of our analysis.
Gopalakrishnan, Jay and Pasciak, Joseph E., "The Convergence of V-Cycle Multigrid Algorithms for Axisymmetric Laplace and Maxwell Equations" (2006). Mathematics and Statistics Faculty Publications and Presentations. 65.