Vortex Trajectories Around a Circular Cylinder in Oscillatory Plus Mean Flow

The vorticity-stream function equations and a third-order in time, second-order in space, three-level predictor-corrector finite-difference scheme has been used to carry out numerical experiments on laminar pulsatile flow (with nonzero mean). The results have revealed, for the first time, the existence of a very interesting wake comprised of three rows of heterostrophic vortices at certain Keulegan-Carpenter numbers and relative current velocities. The existence of such a street has been vindicated by physical experiments. The calculations have also shown that the drag and inertia coefficients for K=4–6 are in reasonable agreement with those obtained experimentally at corresponding relative current velocities.