# Multilevel Mesh Partitioning for Optimising Subdomain Aspect Ratio

**C. Walshaw, M. Cross, R. Diekmann and F. Schlimbach**

### Abstract:

Multilevel algorithms are a successful class of optimisation techniques which address the mesh partitioning problem for mapping meshes onto parallel computers.
They usually combine a graph contraction algorithm together with a local optimisation method which refines the partition at each graph level.
To date these algorithms have been used almost exclusively to minimise the cut-edge weight in the graph with the aim of minimising the parallel communication overhead.
However it has been shown that for certain classes of problem, the convergence of the underlying solution algorithm is strongly influenced by the shape or aspect ratio of the subdomains.
In this paper therefore, we modify the multilevel algorithms in order to optimise a cost function based on aspect ratio.
Several variants of the algorithms are tested and shown to provide excellent results.

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Fri Aug 13 13:41:06 BST 2004