PEGASE - A NAVIER-STOKES SOLVER FOR DIRECT NUMERICAL-SIMULATION OF INCOMPRESSIBLE FLOWS

A hybrid conservative finite difference/finite element scheme is propo sed for the solution of the unsteady incompressible Navier-Stokes equa tions. Using velocity-pressure variables on a non-staggered grid syste m, the solution is obtained with a projection method based on the reso lution of a pressure Poisson equation. The new proposed scheme is deri ved from the finite element spatial discretization using the Galerkin method with piecewise bilinear polynomial basis functions defined on q uadrilateral elements. It is applied to the pressure gradient term and to the non-linear convection term as in the so-called group finite el ement method. It ensures strong coupling between spatial directions, i nhibiting the development of oscillations during long-term computation s, as demonstrated by the validation studies. Two- and three-dimension al unsteady separated flows with open boundaries have been simulated w ith the proposed method using Cartesian uniform mesh grids. Several ex amples of calculations on the backward-facing step configuration are r eported and the results obtained are compared with those given by othe r methods. (C) 1997 by John Wiley & Sons, Ltd.