Model Testing on Cross-Flow Vortex-Induced Vibration in Combined In-Line Current and Oscillatory Flows

The cross-flow vibration of a cylinder in co-linear steady and oscillatory flows is investigated in towing tank for the inline Keulegan Carpenter number varying from 5 to 27 and for the reduced velocity varying from 3 to 19. The reduced velocity is defined by adding together the towing speed and the maximum in-line oscillating velocity. The ratio between the maximum in-line oscillating velocity and the total in-line velocity, i.e. including the towing speed, varies from 0.1 to 0.8. The Reynolds number is in the sub-critical regime. The model test results show that cross-flow vortex-induced vibration (VIV) in combined wave and current flow is significantly different from that in current or wave alone. The response is very much dependent upon the velocity ratio between the current and wave particle velocity.