Calculation of the Flow Field around a Square Section Cylinder undergoing Forced Transverse Oscillations using a Discrete Vortex Method. G.U. Aero report 9814

A Discrete Vortex Method has been developed at the Department of Aerospace Engineering, University of Glasgow, to predict unsteady, incompressible, separated flows around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles which are free to move in the flow. The grid free nature of the method allows analysis of a wide range of problems for both stationary and moving bodies. This paper presents a brief description of the method and presents the results of a validation programme on bluff bodies undergoing forced transverse oscillations. The results demonstrate that the method successfully predicts the vortex lock-in phenomena around the resonance point, as well as capturing the various states of the flow field expected above and below vortex lock-in. Results are presented for the fluctuating lift coefficients, surface pressure coefficients and phase angle, for a square cylinder undergoing transverse oscillations over a range of frequencies and amplitudes. The results from the vortex method show good agreement, both qualitatively and quantitatively, with results from various experimental data