The critical point in vortex-induced vibration of pivoted cylinder
It has been well established that a critical mass ratio for cylinders undergoing vortex-induced vibration (VIV) in a translational system exists. Below this critical point, there exists no de-coherence region and VIV occurs at all velocities above the initial lock-in. While it has been surmised that a corresponding mass moment of inertia ratio must exist for a pivoted cylinder arrangement, there are limited studies published investigating this premise. The aim of this present study then was to examine the VIV critical point for cylinders in a rotational system. The approach adopted involved measuring the VIV amplitude response of a positively buoyant pivoted cylinder at very high reduced velocity. The results of 2 experiments regarding the critical point of a cylinder in a rotational system are presented in this paper. The key finding of this study is the presence of a critical point with a value similar to that of the critical mass ratio in translational systems. This critical point does not however appear to be governed by the mass moment of inertia ratio, but rather by the force moment ratio.