A NON-STAGGERED GRID, FRACTIONAL STEP METHOD FOR TIME-DEPENDENT INCOMPRESSIBLE NAVIER-STOKES EQUATIONS IN CURVILINEAR COORDINATES

A numerical method for solving three-dimensional, time-dependent incompressible Navier-Stokes equations in curvilinear coordinates is presented. The non-staggered-grid method originally developed by C. M. Rhie and W. L. Chow (AlAA J. 21,1525 (1983)) for steady state problems is extended to compute unsteady flows. In the computational space, the Cartesian velocity components and the pressure are defined st the center of a control volume, while the volume fluxes are defined st the mid-point on their corresponding cell faces. The momentum equations are integrated semi-implicitly by the approximate factorization technique. The intermediate velocities are interpolated onto the faces of the control volume to form the source terms of the pressure Poisson equation, which is solved iteratively with a multigrid method. The compatibility condition of the pressure Poisson equation is satisfied in the same manner as in a staggered-grid method; mass conservation can be satisfied to machine accuracy. The pressure boundary condition is derived from the momentum equations. Solutions of both steady and unsteady problems including the large eddy simulation of a rotating and stratified upwelling flow in an irregular container established the favorable accuracy and efficiency of the present method. (C) 1994 Academic Press, Inc.