Further developments of UnTRIM: parallel implementation and its verification

J.A. Jankowski

Abstract. This contribution deals with further developments of UnTRIM, an unstructured-grid, three-dimensional, semi-implicit finite difference finite volume model for the shallow water equations (Casulli, 2002). Attractive numerical properties of the method like its robustness due to the unlimited stability and successes in practical applications spawned efforts aimed at making the available code fit for the high performance computing in order to address larger, complex problems in hydraulic engineering. The paper concentrates on the parallel implementation of the program, based on the domain decomposition method and message passing, which has been achieved without negatively affecting any of the properties of the serial code. A special attention is paid to a new, autonomous parallel streamline backtracking algorithm, which allows using semi-Lagrangian methods in decomposed meshes without compromising the scalability of the code. The new developments have been carefully verified not only with the numerous simple, abstract test cases illustrating the application domain of the code, but also with advanced, high resolution models presently applied for research and engineering projects.

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Reference: Jankowski, J.A. (2007) Further developments of UnTRIM: parallel implementation and its verification. Proceedings of the IAHR Fifth International Symposium on Environmental Hydraulics, (ISEH V), Tempe, Arizona, USA.