Comparisons of the MPI and PVM performances by using structured and unstructured CFD codes

This chapter compares the parallel performances obtainable with two of the most used environments for the development of parallel codes, PVM and MPI, when applied to computational fluid dynamics (CFD) problems. Two CFD codes—ZEN and NUGENS—have been considered in this work, which have been run and tested on several architectures, for obtaining vast information. ZEN is a parallel 3D Multiblock and Multizone Euler/Thin Layer Navier Stokes flow solver for the simulations of subsonic/transonic flow fields around aerodynamics configurations. NUGENS is a 2D flow solver for the resolution of the Euler equations on unstructured meshes. It is based on a Finite Element discretization with the Galerkin approach and the addition of artificial dissipation. The time integration is performed through an explicit Runge-Kutta five stages procedure. The numerical simulations have been executed on three different machines: the SGI Power Challenge supercomputer (16 R10000 processors) installed at CIRA, the SGI Origin 2000 (16 R10000 processors) installed at SGI (Switzerland) and the IBM SP2 (32 ThinII nodes) installed at DLR (Germany). The main aim of this chapter is to provide a comparison between the parallel performances of CFD codes by using these message passing tools. Comparisons between the two environments, in terms of parallel speed-up, have been carried out for all architecture by using both the considered codes.