The effects of attached flexible tail length on the flow structure of an oscillating cylinder

Particle Imaging Velocimetry (PIV) is utilized to investigate the flow structures of an oscillating cylinder attached to a flexible tail. At the same oscillation frequency and amplitude, the mean streamwise velocity along the wake central-line and the mean vertical velocity around the trailing edge of the flexible tail can be greatly increased with the tail length. Meanwhile, the longer the flexible tail is, the larger its deformation is. In order to study the influence of flexible tail length on the wake pattern of the experimental model, the relationships between the swirling strength Λ_ci of vortex structure near the tail end and the velocity of tail trailing edge have been revealed. Moreover, the convection tracks and the Λ_ci of vortex cores for different flexible tails are discussed.