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A three-dimensional, time-dependent free-Lagrange hy drodynamics code has been multitasked and autotasked on a CRAY X-MP/416. The multitasking was done by using the Los Alamos Multitasking Control Library, which is a superset of the CRAY multitasking library. Autotasking is done by using constructs which are only comment cards if the source code is not run through a preprocessor. The three-dimensional algorithm has pre sented a number of problems that simpler algorithms, such as those for one-dimensional hydrodynamics, did not exhibit. Problems in converting the serial code, orig inally written for a CRAY-1, to a multitasking code are discussed. Autotasking of a rewritten version of the code is discussed. Timing results for subroutines and hot spots in the serial code are presented and suggestions for additional tools and debugging aids are given. Theo retical speedup results obtained from Amdahl's law and actual speedup results obtained on a dedicated machine are presented. Suggestions for designing large parallel codes are given.

DISCLAIMER ABSTRACTThe models used to calculate the programmed burn high-explosive lighting times for two-and three-dimensions in the FLAG code are described. FLAG uses an unstructured polyhedra grid. The calculations were compared to exact solutions for a square in two dimensions and for a cube in three dimensions. The maximum error was 3.95 percent in two dimensions and 4.84 percent in three dimensions. The high explosive lighting time model described has the advantage that only one cell at a time needs to be considered.

As part of a program to develop advanced hydrocode design tools, we have implemented a brittle hcture model for glass into the SPHINX smooth particle hydrodynamics code. We have evaluated this model and the code by predicting data fiom one-dimensional flyer plate impacts into glass. Since hctured glass properties, which are needed in the model, are not available, we did sensitivity studies of these properties, as well as sensitivity studies to determine the number of particles needed in the calculations. The numerical results are in good agreement with the data.

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