47 / 2019-08-22 15:29:27

A Second-Order Time-Accurate Fractional-Step Method for Incompressible Flow on Unstructured Grids

fractional-step method; finite volume method; non-staggered unstructured grid.

This paper presented a second-order time-accurate fractional-step method for calculating unsteady incompressible flows on unstructured grids. The procedure used the fractional-step method for solving the unsteady incompressible flows. A non-staggered grid system was employed due to its simplicity and easy extending to three dimensions. The momentum interpolation method, proposed by Rhie and Chow and further extended to calculate the unsteady flow by Zang et al., was applied to the unstructured grids to eliminate the spurious pressure oscillations on non-staggered grids. Finite volume method was used for the spatial discretization and the flow variables at the cell face were obtained using the QUICK scheme in NVSF form. The Crank-Nicolson scheme was used to resolve the time step restriction and reduce the required CPU time for complex geometries. Both the momentum equations and the Poisson equation of pressure were solved by the Newton-iterative method. The procedure was validated by three benchmark testing cases. The results agreed well with the benchmark numerical solutions or experimental data. These prove that the present method is accurate and efficient.