Experience in Parallelizing Mesh Generation Code with High Performance Fortran

Delaunay triangulation exposes highly irregular computation patterns, which imposes challenge on high-level language designers and implementors, in terms of adequate expressiveness of the language and efficient implementation of supported language features. This paper reports an implementation of divide-and-conquer parallel Delaunay triangulation with High Performance Fortran (HPF), a high-level data-parallel language. We show that with careful control of data distribution, we are able to parallelize the program using HPF's standard directives. 1 Introduction We report experience and result from parallelizing an existing mesh generation code written in Fortran using HPF data mapping directives. The original code is written in Fortran 77 and it generates mesh points and their Delaunay triangulation when given the boundary of a 2-D model. The need for parallel mesh generation comes from the need to solve very large models in finite element and finite volume analysis. It is now common to..

Unstructured parallel grid generation.

The ultimate goal of this study is to develop a 'tool' by which large-scale unstructured grids for realistic engineering problems can be generated efficiently on any parallel computer platform. The adopted strategy is based upon a geometrical partitioning concept, where the computational domain is sub-divided into a number of sub-domains which are then gridded independently in parallel. This study focuses on three-dimensional applications only, and it implements a Delaunay triangulation based generator to generate the sub-domain grids. Two different approaches have been investigated, where the variations between them are limited to (i) the domain decomposition and (ii) the inter-domain boundary gridding algorithms only. In order to carry out the domain decomposition task, the first approach requires an initial tetrahedral grid to be constructed, whilst the second approach operates directly on the boundary triangular grid. Hence, this thesis will refer to the first approach as 'indirect decomposition method' and to the second as 'direct decomposition method'. Work presented in this thesis also concerns the development of a framework in which all different sub-algorithms are integrated in combination with a specially designed parallel processing technique, termed as Dynamic Parallel Processing (DPP). The framework adopts the Message Passing Library (MPL) programming model and implements a Single Program Multiple Data (SPMD) structure with a Manager/Workers mechanism. The DPP provides great flexibility and efficiency in exploiting the available computing resources. The framework has proved to be a very effective tool for generating large-scale grids. Grids of realistic engineering problems and to the order of 115 million elements, generated using one processor on an SGI Challenge machine with 512 MBytes of shared memory, will be presented