Approach to damping effects of fairings on VIV of flexible cylinder with three-dimensional numerical simulations

Abstract

Vortex-induced vibration (VIV), which will lead to the fatigue damage on coastal structures like flexible cylinders, has attracted considerable attention. The object of this study is to investigate the VIV phenomenon of flexible cylinder and the damping effects of fairings which could be used as vortex-suppressing devices, with three-dimensional (3D) fluid-structure interaction considered. In this paper, a 3D finite element (FE) model is established with the cylinder simulated by solid elements, the fluid field by the Arbitrary Lagrangian Eulerian (ALE) scheme, and the pipe surface by the moving boundary. Non-uniform mesh in different region and dynamic mesh in the area around the pipe are used to better simulate the pipe and the fluid field. The feasibility of the model is verified. The correlations between the vibration amplitude and the vortex shedding frequency are depicted, with the lock-in phenomenon captured. The displacement responses of the pipe are calculated with the damping effects considered, which is reflected not only in reducing the vibration amplitude of the pipe, but also in raising the flow rates for the lock-in region. This study will provide useful theoretical reference for vibration control of the VIV phenomenon of flexible cylinder.