A COMPARISON OF SEGREGATED AND COUPLED METHODS FOR THE SOLUTION OF THE INCOMPRESSIBLE NAVIER-STOKES EQUATIONS

Three different solution methods for the finite-volume discretized inc ompressible Navier-Stokes equations have been tested: segregated appro aches, built around coupling methods such as SIMPLE, SIMPLER and PISO plus a line Gauss-Seidel linear solver; coupled methods, incorporating a penalty formulation to eliminate zero diagonal elements in the coef ficient matrices, plus preconditioned GMRES as a linear solver,- and a FAS-full multigrid algorithm accelerating a classical segregated meth od based upon SIMPLE and the line Gauss-Seidel solver. Results demonst rate that the coupled method compares favourably to the segregated tec hnique at small grid sizes but becomes too expensive for large problem s, The FAS-fun multigrid algorithm outperforms the other two methods w hen large numbers of nodes are employed in the simulation.