Simulation of vortex shedding past a square cylinder near a wall

Calculations are reported for the flow past a square cylinder at Re = 22,000 placed at various distances from an adjacent wall, including the limiting case without wall influence. Experiments have indicated that unsteady vortex shedding is suppressed when the wall is relatively close to the cylinder. Two-dimensional (2-D) unsteady equations are solved which allow any periodic shedding motion to be resolved; the superimposed turbulent fluctuations are simulated with two versions of the k-epsilon turbulence model: the standard k-epsilon model and the modification attributable to Kato and Launder (1993), which eliminates the excessive turbulent kinetic energy production in stagnation regions produced by the standard model. Wall functions are used with both versions. The standard model was found to damp the shedding motion unrealistically so that shedding was suppressed at considerably larger gap widths than observed experimentally. The Kato-Launder modification yields reasonable predictions over the full range of gap widths; for G(W)/D = 0.75 a quantitative comparison is presented with the authors' phase-resolved experiments, which shows fairly good accord.