NUMERICAL STUDY OF HIGH-REYNOLDS-NUMBER FLOW PAST A BLUFF OBJECT

A semi-explicit finite difference scheme is proposed to study unsteady two-dimensional, incompressible flow past a bluff object at high Reyn olds number. The bluff object comes from a class of elliptical cylinde rs in which the aspect ratio and the angle of attack are two controlle d parameters. Associated with the streamfunction-vorticity formulation , the interior vorticity, streamfunction and wall Vorticity are update d in turn for each time step. The streamfunction and wall vorticity ar e solved by means of a multigrid method and a projection method respec tively. In regard to the vorticity transport equation, implicitness is merely associated with the diffusion operator, which can be made semi -explicit via approximate factorization. Low-diffusive upwinding is de vised to handle the convection part. Numerical results are reported fo r Reynolds numbers up to 40,000. Comparisons with other numerical or p hysical experiments are included.