A MULTIGRID PROCEDURE FOR 3-DIMENSIONAL FLOWS ON NONORTHOGONAL COLLOCATED GRIDS

The development of a multigrid solution algorithm for the computation of three-dimensional laminar fully-elliptic incompressible flows is pr esented. The procedure utilizes a non-orthogonal collocated arrangemen t of the primitive variables in generalized curvilinear co-ordinates. The momentum and continuity equations are solved in a decoupled manner and a pressure-correction equation is used to update the pressures su ch that the fluxes at the cell faces satisfy local mass continuity. Th e convergence of the numerical solution is accelerated by the use of a Full Approximation Storage (FAS) multigrid technique. Numerical compu tations of the laminar flow in a 90 degrees strongly curved pipe are p erformed for several finite-volume grids and Reynolds numbers to demon strate the efficiency of the present numerical scheme. The rates of co nvergence, computational times, and multigrid performance indicators a re reported for each case. Despite the additional computational overhe ad required in the restriction and prolongation phases of the multigri d cycling, the superior convergence of the present algorithm is shown to result in significantly reduced overall CPU times.