Numerical investigation of flow-induced vibrations of cylindrical structures

Abstract

To expand the understanding of flow past and flow-induced vibrations of circular cylinders under complex flow conditions, extensive investigation through two- and three-dimensional numerical simulations are conducted in this thesis. The thesis starts with a two-dimensional numerical study to investigate the effect of a plane boundary on vortex-induced vibrations of circular cylinder both in transverse and inline direction subject to oscillatory flow. The effects of the gap between circular cylinder and plane boundary and Keulegan-Carpenter (KC) number on VIV are discovered. Next, the study is extended to investigate the effect of high-speed rotation on the vortex-induced vibration of the cylinder in the cross-flow direction subject to uniform flow using two-dimensional numerical simulations. The amplitude response is classified in to different regimes both as a function of reduced velocity and rotation rate. In order to better understand the dynamics of rotating cylinder, three-dimensional numerical simulations are performed next for a range of high-speed rotation rates and Reynolds number from Re=100 to 500 under uniform flow conditions. The results of the study are presented in the form of map between rotation rate and Reynolds number identifying different flow structures as a function of rotation rate and Reynolds number. A detailed analysis of flow structures is also presented in order to improve the understanding of the physics of the rotating cylinders. The study is further extended to three-dimensional numerical investigation of flow-induced vibrations of rotating circular cylinders at Re=500 in the cross-flow direction subject to uniform flow. It is found the rotation rate has significant effect on the 'Lock-in' regime as the rotation rate is increased. In addition, three-dimensional numerical simulations are carried out next to investigate the VIV around two circular cylinders in side-by-side arrangement to study the effect of gap ratio on the interference between two cylinders.

Date of Award	2019
Original language	English