Modeling of vortex-induced vibrations for a flexible tube subjected to both internal fluid flow and external cross-flow

Abstract

The full derivation of the partial differential equations of motion for a flexible tube with internal and external fluids is presented. The modeling of this coupling system is realized using the dynamics of the flexible tube coupled with the fluid forces and the new improved wake oscillator model respectively. This results in two theoretical models. Firstly, the response of the tube under cross-flow is predicted using the fluid forces obtained from a fluid–structure interaction simulation. Secondly, a new improved wake oscillator model for predicting the vortex-induced vibration is proposed which is used to simulate the coupling between flexible tube and cross-flow. The results show that, the theoretical model based on fluid force underestimates the amplitude especially fails in predicting the amplitude during lock-in. The theoretical model based on the new improved wake oscillator is feasible to predict the vibrations of flexible tube under internal flow and cross-flow.