The effectiveness of domain balancing strategies on workstation clusters demonstrated by viscous flow problems

We consider several aspects of efficient numerical simulation of viscous compressible flow on both homogeneous and heterogeneous workstation-clusters. We consider dedicated systems, as well as clusters operating in a multi-user environment. For dedicated homogeneous clusters, we show that with respect to the turn-around time, there is an optimal number of workstations to solve a given flow-problem. This number depends on the actual implementation of the solver. For non-dedicated heterogeneous clusters we apply dynamic domain-balancing techniques in order to obtain an optimal turn-around time for the flow-simulation job only, taking into account the activities on the cluster arising from the other applications. We show that the decision which technique should be used depends on various aspects, such as the character of the load-fluctuations arising from the other applications, whether the flow-simulation job is computationally intensive, and the underlying hardware. The effects of these aspects on this decision are analyzed. Although it can be concluded that no domain-balancing technique is the best under arbitrary circumstances, such an analysis may guide the decision for a particular load-situation. Moreover, we indicate how such a decision can be supported by a comparison of the various balancing strategies using a simulation study. This is illustrated for a specific load-situation