NUMERICAL-SIMULATION OF SHEAR EFFECT ON VORTEX SHEDDING BEHIND A SQUARE CYLINDER

This paper is concerned with the numerical simulation of the flow stru cture around a square cylinder in a uniform shear how. The calculation s were conducted by solving the unsteady 2D Navier-Stokes equations wi th a finite difference method. The effect of the shear parameter K of the approaching flow on the vortex-shedding Strouhal number and the fo rce coefficients acting on the square cylinder is investigated in the range K=0.0-0.25 at various Reynolds numbers from 500 to 1500. The com putational results are compared with some existing experimental data a nd previous studies. The effect of shear rate on the Strouhal number a nd the force acting on the cylinder has a tendency to reduce the oscil lation. The Strouhal number, mean drag and amplitude of the fluctuatin g force tend to decrease as the shear rate increases, but show no sign ificant change at low shear rate. Increasing the Reynolds number decre ases the Strouhal number and increases the force acting on the cylinde r. At high shear rate the shedding frequencies of the fluctuating drag and lift coefficients are identical. (C) 1997 John Wiley & Sons, Ltd.