OUT-OF-CORE SOLVER FOR LARGE, MULTIZONE BOUNDARY-ELEMENT MATRICES

In this paper an out-of-core solver is developed for a three-dimension al elastostatic boundary element program. This program includes multi- regions which enables a large model to be divided into a number of hom ogeneous sub-models, each with their own material properties. The syst em matrix produced by multi-regions is sparse, blocked and unsymmetric in character and so reduces disc space and solution time. The solver presented in this paper utilizes efficiently the structure of this mat rix by holding only non-zero parts of this matrix in a sequential, unf ormatted direct access file, reading in as much of the file as possibl e into the working space, performing Gauss elimination, then writing p art of the matrix back to file. The maximum utilization of working spa ce is particularly important on vector machines as vector activity is maximized whilst record read/write is minimized. The effect of multi-r egions on CPU is demonstrated on both the CONVEX and GRAY machines.