Vector Algorithm for Large-Memory CYBER 205 Simulations of Euler Flows

Summary

The paper reviews a finite-volume method for the large-scale numerical simulation of fluid flow and discusses the vector coding and execution of the procedure on the CYBER 205. With the proper structure given to the data by the grid transformation each coordinate direction can be differenced throughout the entire grid in one vector operation. Boundary conditions must be interleaved which tends to inhibit the concurrency of the overall scheme, but a stragey of no data motion together with only inner-loop vectorization is judged to be the best compromise. The computed example of transonic vortex flow separating from the sharp leading edge of a delta wing demonstrates the processing performance of the procedure. Vectors over 40, 000 elements long are obtained, and a rate of over 125 megaflops, sustained over the entire computation, is achieved when the entire data set is resident in real memory. Attemps to use secondary memory, either explicitly or with virtual management, greatly degrades the performance.

also adjunct prefessor of computational fluid dynamics, Royal Institute of Technology, Stockholm, Sweden