PARALLELIZATION STRATEGIES FOR SMOOTH-PARTICLE HYDRODYNAMICS

THE TECHNIQUE OF SMOOTH-PARTICLE HYDRODYNAMICS (SPH) HAS PROVED TO BE VERY USEFUL IN TREATING CERTAIN CLASSES OF HYDRODYNAMICS PROBLEMS, INCLUDING THREE-DIMENSIONAL MODELING OF IMPLOSIONS AND EXPLOSIONS, LASER-TARGET INTERACTIONS, AND HIGH VELOCITY IMPACT. IN THREE-DIMENSIONAL MODELING, SPH HAS UNRIVALED SIMPLICITY AS A GRIDLESS, LAGRANGIAN TECHNIQUE. IN SPH, THE CONCEPT OF FLUID ELEMENTS DEFINED BY A GRID IS REPLACED BY A COLLECTION OF PARTICLES, OR MASS POINTS, WITH FLUID PROPERTIES SUCH AS MASS, VELOCITY, AND PRESSURE DEFINED AT THE PARTICLE POSITIONS. THUS, SPH AVOIDS PROBLEMS ASSOCIATED WITH MESH TANGLING AND DISTORTION, WHICH ARE PARTICULARLY DIFFICULT IN THREE-DIMENSIONAL MODELING. A SERIAL SPH CODE HAS BEEN DEVELOPED AND IS IN USE AT BOTH LOS ALAMOS NATIONAL LABORATORY AND LAWRENCE LIVERMORE NATIONAL LABORATORY. IN PHASE I, A SCHEME TO EFFICIENTLY PARALLELIZE THE SPH TECHNIQUE IS BEING DEVELOPED TO EXPLOIT THE CAPABILITIES OF NEW HIGH PERFORMANCE MACHINES. THE SCHEME WILL ACHIEVE DYNAMIC LOAD BALANCE THROUGH THE USE OF GLOBAL SPATIAL DECOMPOSITION. NEAREST NEIGHBORS ARE BEING IDENTIFIED BY USING A DISTRIBUTED OCTTREE. ALGORITHMS ARE BEING IMPLEMENTED ON A 16-NODE INTEL IPSC/860. THE CODE IS BEING BENCHMARKED AGAINST A SERIAL VERSION, AND LOAD BALANCE AND COMMUNICATION INEFFICIENCIES ARE BEING MEASURED. A SUCCESSFUL PHASE I WILL DEMONSTRATE THAT THE BASIC SMOOTH-PARTICLE HYDRODYNAMICS TECHNIQUE CAN BE EFFICIENTLY PARALLELIZED ON A MULTIPLE-INSTRUCTION, MULTIPLE-DATA ARCHITECTURE. IT WILL SHOW THAT THE ALGORITHMS DEVELOPED ARE SCALABLE TO A LARGE NUMBER OF PROCESSORS.