Mitigation of Vortex-Induced Vibration in Offshore Structures

Abstract

Vortex-induced vibration (VIV) study of any offshore structure is of paramount importance to check the structural stability. VIV poses a significant concern for these structures, as the excessive vibration can lead to fatigue damage and structural failure. Mooring lines, risers, pipelines, and other attachments can also get damaged in case of offshore structures. When the shedding frequency approaches the structure's shedding frequency, these vibrations can be major and perhaps dangerous. VIV can occur at low as well as high Reynold's number regime. Because of rising demand for crude oil, offshore gas, and oil, exploration has been shifted to deeper sea levels. Offshore floating wind turbines are used to conserve energy and generate electricity. It can further help to reduce visual pollution and achieve stronger and more constant winds. Floating offshore wind turbines are considered a viable solution in ocean depths more than 50 to 60 meters and with significant wind resources. As an emerging technology, it can utilize less foundation material, shorten the installation and decommissioning times, and create more wind energy. New dangers can be mitigated by employing commercially available bottom fixed turbines and well-known oil and gas technologies for floaters. VIV can cause large-amplitude vibrations of tethered structures in the ocean. Thus, the effect of VIV on floating structures needs to be studied. The flow-induced response of a floating structure is generally checked for crossflow. In this study a response reduction technique is proposed based on the in-house modelled two-way coupled interaction of fluid and structure due to vortex-induced motion.