Defining a Parameter of Effectiveness for the Suppression of Vortex-Induced Vibration

The vortex-induced vibration (VIV) phenomenon is a very important issue in ocean and offshore engineering. When bluff bodies are immersed in a current, the boundary layers separate and form shear layers that can interact causing a periodic vortex shedding. In such condition, the forces acting on the body can make it vibrate. In the offshore industry, among other engineering applications, the vibration of structures can cause fatigue problems, reducing the life span of the element. To reduce the vortex-induced vibration effect suppressors can be employed in order to avoid the body to move, or at least, reduce the amplitude of vibration. There is a great number of suppressor types, like strakes, splitter plates, shrouds, etc; and each one has its own flow mechanisms to avoid VIV. Until now there is no simple way to compare the results and effectiveness of each suppressor. The purpose of this work is to define a parameter called suppressor effectiveness, based on the amplitude of vibration and the reduced velocity range, and use the suppressor effectiveness to compare different suppressors. The data used in the comparisons was obtained from experiments by the authors and collected from the literature.