Numerical simulation of laminar flow past an oscillating circular cylinder

The problem of unsteady, two dimensional laminar flow past a circular cylinder which performs recti-linear oscillations at an arbitrary angle η with respect to the oncoming uniform flow is considered. The governing Navier-Stokes equations are expressed in terms of a stream-function/vorticity formulation are solved numerically for a fixed Reynolds number R=855. The calculations are performed when the maximum displacement amplitude-to-cylinder radius ratio is 0.26. The recti-linear oscillations are only allowed when η=45o. A boundary-layer type transformation is adopted to scale out the singular nature in the vorticity at the start of the motion. The object of this study is to examine the effect of increase of frequency of the recti-linear oscillations on the near wake structure as well as the hydrodynamic forces acting on the cylinder. The results of this study are in good agreement with previous experimental predictions. (author)