MULTIGRID SOLUTION OF THE NAVIER-STOKES EQUATIONS ON HIGHLY STRETCHED GRIDS

Relaxation-based multigrid solvers for the steady incompressible Navier-Stokes equations are examined to determine their computational speed and robustness. Four relaxation methods were used as smoothers in a common tailored multigrid procedure. The resulting solvers were applied to three two-dimensional flow problems, over a range of Reynolds numbers, on both uniform and highly stretched grids. In all cases the L2 norm of the velocity changes is reduced to 10(-6) in a few 10's of fine-grid sweeps. The results of the study are used to draw conclusions on the strengths and weaknesses of the individual relaxation methods as well as those of the overall multigrid procedure when used as a solver on highly stretched grids.