Parallel computing in aerospace using multi‐block grids. Part 1: Application to grid generation

Abstract

AbstractThe present paper describes the implementation of multi‐block codes, used to model complex 2‐D geometries for applications in computational fluid dynamics on massively parallel architectures. The work starts with a brief description of ongoing and planned major aerospace projects and gives an estimate of the computing power needed. In order to provide this computational speed, one has to resort to massively parallel systems. In the first section the essential features of multi‐block grids, along with the grid generation equations are discussed and it is shown that overlapping multi‐block grids are inherently parallel by construction. Since the number of blocks is not fixed, but can be matched to a large extent to the number of available processors, there are no principal limitations of this parallelization approach, provided the ratio of computation time to communication time remains large enough, which leads to the discussion of problem scalability. The details of implementation on the Intel iPSC/2 of a general 2‐D multi‐block mesh‐generation code are outlined in sections 2 and 3, together with the listings of the major communication function (Section 4). In section 5 the results for this code are presented, clearly demonstrating that the multi‐block concept is a viable tool for massively parallel computers, which can be applied to virtually all problems in science and engineering where computational meshes are used. In section 5.2 an outlook on the parallelization of more complex problems is given, and estimates for speed‐up and efficiency, based on the present experiences, are provided. It turns out that, as long as computation dominates communication time, which is usually the case for complex aerospace applications, parallelization will be the tool to provide the additional orders of magnitude of computing power needed to routinely design and analyse future aircraft as well as spacecraft, in particular at high Mach numbers, when chemical reactions become important.