Multigrid on unstructured grids using an auxiliary set of structured grids

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:440711

Douglas, C C; Malhotra, S; Schultz, M H ^[1]

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1. Yale Univ., New Haven, CT (United States)

Unstructured grids do not have a convenient and natural multigrid framework for actually computing and maintaining a high floating point rate on standard computers. In fact, just the coarsening process is expensive for many applications. Since unstructured grids play a vital role in many scientific computing applications, many modifications have been proposed to solve this problem. One suggested solution is to map the original unstructured grid onto a structured grid. This can be used as a fine grid in a standard multigrid algorithm to precondition the original problem on the unstructured grid. We show that unless extreme care is taken, this mapping can lead to a system with a high condition number which eliminates the usefulness of the multigrid method. Theorems with lower and upper bounds are provided. Simple examples show that the upper bounds are sharp.

• Research Organization: Front Range Scientific Computations, Inc., Lakewood, CO (United States)
• OSTI ID: 440711
• Report Number(s): CONF-9604167--Vol.2; ON: DE96015307
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
ALGORITHMS
COMPUTER CALCULATIONS
COORDINATES
ITERATIVE METHODS
MODIFICATIONS