Leveraging Multicore Cluster Nodes by Adding OpenMP to Flow Solvers Parallelized with MPI

MPI is the predominant model for parallel programming in technical high performance computing. With an increasing number of cores and threads in cluster nodes the question arises whether pure MPI is an appropriate approach to utilize today�s compute clusters or if it is profitable to add another layer of parallelism within the nodes by applying OpenMP on a lower level. Investing a limited amount of manpower, we add OpenMP directives to three MPI production codes and compare and analyze the performance varying the number of MPI processes per node and the number of OpenMP threads per MPI process on current CMP/CMT architectures