In this paper, we examine various modeling and simulation applications of cluster computing using a Beowulf cluster. These applications are used to investigate the performance of our cluster in terms of computational speedup, scalability, and communications. The applications include solution of linear systems by Jacobi iteration, distributed image generation, and the finite difference time domain solution of Maxwell's equations. It is observed that the computational load for these applications must be large compared to the communication overhead to take advantage of the speedup obtained using parallel computing. For the applications reviewed here, this condition is increasingly satisfied as the problem size becomes larger or as higher resolution is required.