Parallelization of a simulation code for reactive flows on the intel paragon

The paper shows the implementation of a 3D simulation code for turbulent flow and combustion processes in full-scale utility boilers on an Intel Paragon XP/S computer. For the portable parallelization, an explicit approach is chosen using a domain decomposition method for the static subdivision of the numerical grid together with the SPMD programming model. The measured speedup for the presented case using a coarse grid is good, although some numerical requirements restrict the implemented message passing to strongly synchronized communication. On the Paragon, the NX message passing library is used for the computations. Furthermore, MPI and PVM are applied and their pros and cons on this computer are described. In addition to the basic message passing techniques for local and global communication, other possibilities are investigated. Besides the applicability of the vectorizing capability of the compiler, the influence of the I/O performance during computations is demonstrated. The scalability of the parallel application is presented for a refined discretization.