The ARGESIM benchmark CP2 consists of three different tasks to study current technologies for the parallelization of simulation programs, two of which have been addressed in a previous publication. The third one is the study of the fluid flow in a special geometry using the Lattice Boltzmann method. The task is studied with two methods for up to 256 cores, again using the MPI message passing library Open MPI and Matlab from The MathWorks in combination with the Parallel Computing Toolbox. Solutions with different grid sizes are compared with each other in terms of runtime and speedup. The Open MPI version generally shows good speedups even for large core numbers, while the Matlab version has poor results for 32 cores or more. On the other hand, the scalar Matlab version is several times faster than the Open MPI version, leading to a smaller runtime for up to 32 cores.