Highly parallel computing of a multigrid solver for 3D Navier-Stokes equations

In order to efficiently obtain all frequencies of the solution, a multigrid solver is used to solve the Navier-Stokes equations for incompressible flows. The method uses a cell-by-cell Gauss-Seidel smoother that is not straightforwardly parallelizable. Moreover the coarsest grids are very coarse and cannot be solved in parallel. The proposed method splits the 3D Cartesian computational domain into well-balanced sub-domains with respect to two dimensions. Efficient parallel procedures using MPI libraries permit us to get a high strong and weak scalability of the whole parallel software. Comparison is done between MPI and hybrid MPI/OpenMP parallelism.