On overlapping partitions

Parallelization strategies based on domain partitioning techniques have been widely adopted for parallel finite element computations because of their suitability to distributed memory platforms. In most cases, this parallelization is based on non-overlapping partitions especially for Computational Structural Mechanics applications. However, finite volume (or mixed finite element/finite volume) discretization methods, which are frequently implemented in Computational Fluid Dynamics applications, generally require the use of overlapping mesh partitions to keep the parallelization work simple. Unfortunately, many tools on which the partitioning step relies give poor results when asked for overlapping partitions. In this paper, we describe an efficient method to transform a non-overlapping partition of a domain into an overlapping one. We also propose an optimization strategy for overlapping partitions that mainly aims at reducing the computational load unbalance as well as the size of the interfaces. The new algorithms demonstrate significant improvements as they are applied to generate overlapping partitions in the context of a parallel mixed finite element/finite volume three-dimensional flow solver.