Parallel distributed FFT-based solvers for 3-D Poisson problems in Meso-scale atmospheric simulations

Fast Poisson solvers based on fast Fourier transform (FFT) computations are among the fastest techniques to solve Poisson equation on uniform grids. I n this paper. the authors present two parallel distributed implementations of a 3-D fast Poisson solver in the context of the atmospheric simulation c ode. The first approach consists of implementing data movement between each computational step so that no elementary computational routine involves co mmunication. The second approach aims at reducing the global data movement and requires the parallelization of one step of the fast Poisson solver. Ex perimental results on a 128-node Cray T3E are presented to illustrate the a dvantages and drawbacks of each approach.