Coupled axial/lateral VIV of marine risers in sheared currents

Hossein Zanganeh, Narakorn Srinil

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

Abstract

Modelling and prediction of vortex-induced vibrations (VIV) of marine risers is a challenging task due to the associated multi degrees of freedom in both cross-flow/in-line directions and the multi-mode fluid-structure interactions. In addition, the axial motion and its geometrically nonlinear coupling with lateral responses can be significant, especially at higher-order modes. Nevertheless, several papers in the literature dealing with VIV predictions have often overlooked such aspects. Therefore, this study aims to investigate and understand the effect of axial or longitudinal motion through a theoretical model and numerical approach in time domain. Attention is paid to VIV of vertical risers subjected to linearly sheared currents. To capture a three-dimensional aspect of the flexible cylinder experiencing VIV, a semiempirical model is developed consisting of nonlinear equations of cross-flow, in-line and axial structural oscillations which are coupled with the distributed van der Pol-type wakeoscillators modelling the fluctuating fluid lift/drag forces. The mean drag force is also taken into account. These model equations are numerically solved via a space-time finite difference scheme, and the obtained numerical results highlight several aspects of VIV of elastic cylinders along with the axial motion effects. Apart from the validation of the numerical model with published experimental results, this study reveals how the effect of axial motion and its nonlinear coupling with the two lateral cross-flow/in-line motions can be very important. These depend on the flow velocity, the fluid-structure parameters, the single or multi-mode lock-in condition, and the standing-wave or travelling-wave feature. We recommend that the axial response should be accounted for in VIV analysis and prediction model.

Original languageEnglish
Title of host publicationProceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE
Number of pages9
Volume2
DOIs
Publication statusPublished - 2015
EventASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2015 - St. John's, Canada
Duration: 31 May 20155 Jun 2015

Conference

ConferenceASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2015
CountryCanada
CitySt. John's
Period31/05/155/06/15

Keywords

  • vortex induced vibration
  • currents
  • marine drilling risers

Fingerprint Dive into the research topics of 'Coupled axial/lateral VIV of marine risers in sheared currents'. Together they form a unique fingerprint.

Cite this