- 1 - PERFORMANCE OF THE SHALLOW WATER EQUATIONS ON THE CM - 200 and CM - 5

We describe the implementation of a fluid dynamical benchmark on two Thinking Machines Corporation parallel computers the 65,536 processor CM-200 computer and the 1024-node CM-5 computer. The benchmark, the Shallow Water Equations, is frequently used as a model for both oceanographic and atmospheric circulation. We describe the steps involved in implementing the algorithm on the computers and we provide details of resulting performance. We have measured 5.2 Gflops (64-bit arithmetic) and 8.1 Gflops (32-bit) on the CM-200 while the CM-5 delivers 22.1 Gflops (64-bit) and 24 Gflops (32-bit). For comparison, performance of 1.53 Gflops was measured for the same algorithm on the CRAY Y-MP/8, 1.28 Gflops on the 256-node SUPRENUM-1 and 0.54 Gflops was measured on the 128-node Intel iPSC/860. * To appear in Proceedings of the Fifth Workshop of the European Centre for Medium-Range Weather Forecasts on "Uses of Parallel Processors in Meteorology", Nov. 23-27, 1992. † Research supported by the Air Force Office of Scientific Research, under grant AFOSR-89-0422 and by NSF Grand Challenge Applications Group grant ASC-9217394.