Dynamics of a vertical riser with weak structural nonlinearity excited by wakes

Marko Keber, Marian Wiercigroch

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41 Citations (Scopus)

Abstract

In this paper we investigate the effect of a weak structural nonlinearity on the dynamical behaviour of a vertical offshore riser subjected to vortex-induced vibration (VIV). Coupling of the riser dynamics with the flow of the surrounding fluid is achieved by attaching a wake oscillator to a reduced model of the structure, which is obtained through the application of the invariant manifold technique for the derivation of nonlinear normal modes.

By comparing the free responses of the linear and the nonlinear structure, it was found that the structural nonlinearity has a stiffening effect on the oscillation of the riser, which becomes more pronounced when the internal flow is incorporated into the model. Consequently, in the coupled system, the response is considerably modified for the structure as well as for the fluid variable. Crown Copyright (c) 2008 Published by Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)685-699
Number of pages15
JournalJournal of Sound and Vibration
Volume315
Issue number3
Early online date2 May 2008
DOIs
Publication statusPublished - 19 Aug 2008

Keywords

  • vortex-induced vibratons
  • normal-modes
  • continous systems
  • marine risers
  • lock-in
  • part 1
  • long
  • prediction
  • cylinders
  • fluid

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