Entwicklung und Implementierung einer dreidimensionalen Partitionierungsstrategie fuer das Programm TRACE auf einem massiv-parallelen Rechner

This report describes a strategy for domain decomposition of a regular finite element grid to be calculated on a parallel computer with distributed memory. The strategy is implemented and performed with the program TRACE, which is a FORTRAN 77 written code for the simulation of hydrological problems. The parallelization of this program is based on the Schwarz method, which decomposes the global grid in several overlapping partial grids. Because of this decomposition method, some nodal points of the global finite element grid can exist in up to eight partial grids and must be locally calculated for each grid. To minimize this extra calculation due to the domain decomposition, a function will be defined, which allows to determine the decomposition with the least redundant calculations. Because of the Schwarz method, some results for certain nodal points must be exchanged during calculation. A partial grid can get results of up to 26 adjacent grids. In the report, the structure of the domains to be exchanged will be explained, and the required changes and extensions of the program TRACE will be described. TRACE has been executed on an Intel Paragon with two different finite element grids, which are based on up to 256000 nodal points. The influence of a changing number of processing elements and a variation of the overlapping domain will be examined. (orig.)SIGLEAvailable from TIB Hannover: RA 831(3157) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman