
Accession Number : ADA324495
Title : A Note on MultiBlock Relaxation Schemes for Multigrid Solvers.
Descriptive Note : Contract rept.,
Corporate Author : INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
Personal Author(s) : Jones, Jim E. ; Melson, N. D.
PDF Url : ADA324495
Report Date : FEB 1997
Pagination or Media Count : 13
Abstract : Efficient and robust multigrid solvers for anisotropic problems typically use either semicoarsened grids or implicit smoothers  line relaxation in 2D and plane relaxation in 3D. However, both of these may be difficult to implement in codes using multiblock structured grids where there may be no natural definition of a global line or plane. These multiblock structured grids are often used in fluid dynamic applications to capture complex geometries and/or to facilitate parallel processing. In this paper, we investigate the performance of multigrid algorithms using implicit smoothers within the blocks of a such a grid. By looking at a model problem, the 2D anisotropic diffusion equation, we show that true multigrid efficiency is achieved only when the block sizes are proportional to the strength of the anisotropy. Further, the blocks must overlap and the size of the overlap must again be proportional to the strength of the anisotropy.
Descriptors : *ALGORITHMS, *PARALLEL PROCESSING, MATHEMATICAL MODELS, GRIDS, COMPUTATIONAL FLUID DYNAMICS, FINITE DIFFERENCE THEORY, POLYNOMIALS, PARTIAL DIFFERENTIAL EQUATIONS, APPLIED MATHEMATICS.
Subject Categories : Operations Research
Distribution Statement : APPROVED FOR PUBLIC RELEASE