Efficient Parallel Algorithms for Computational Fluid Dynamics Vivek Sarin Department of Computer Sciences, Purdue University, West Lafayette, IN 47907 Email: sarin@cs.purdue.edu URL: http://www.cs.purdue.edu/homes/sarin Phone: (765)494-7816, FAX: (765)494-0739 Abstract This talk addresses a number of challenging issues in developing parallel algorithms for large scale scientific simulations. We will present recent results from the simulation of particles in fluids, a problem of great interest to numerous industries, e.g., the petroleum industry. As part of a Grand Challenge project, we have developed two state-of-the-art packages called Particle Movers based on distinct modeling approaches, and have implemented them on several parallel platforms. The most time-consuming component of these simulations is the solution of nonsymmetric, indefinite, sparse linear systems at each time step. This poses significant challenges in developing preconditioners for iterative solvers that are robust and effective in addition to being parallelizable. We have developed a number of innovative techniques that include a novel multilevel algorithm to represent discrete divergence-free space for incompressible fluids and optimal matrix-free parallel preconditioners for enforcing the rigid-body motion of the particles. Our approach combines robust and effective preconditioning with excellent parallel performance, and is more effective than other techniques for fluid problems. Using our techniques, realistic three dimensional flows with thousands of particles have been simulated for the first time on high performance architectures such as the SGI Origin2000. Ongoing work supported by a KDI award extends this work to various types of fluids. Relevant publications and additional details are available at http://www.cs.purdue.edu/homes/sarin.