Drag amplification of long flexible riser models undergoing multi-mode VIV in uniform currents

Shan Huang, Mahdi Khorasanchi, Kjell Herfjord

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37 Citations (Scopus)


Measurement data of longf lexibleriser models are used to study the drag amplification due tomulti-mode vortex induced vibration (VIV). The riser model was towed in a towing tank, and vibration along its length was measured indirectly at a set of discrete points using accelerometers, along with the total drag and lift forces on the model. These data were used to fit expressions for the drag amplification taking into account the spatial variation of the vibration amplitude along the riser length.The result swere compared with the existing empirical expression used in the VIV analysis tool SHEAR7 as wellas other test data. It was found that the expression in SHEAR7 agrees well with the test data. However, for larger vibration amplitudes, it appears to under-predict the drag amplification.
Original languageEnglish
Pages (from-to)342-353
Number of pages12
JournalJournal of Fluids and Structures
Issue number3
Publication statusPublished - Apr 2011


  • vortex induced vibration
  • VIV
  • drag amplification
  • flexible cylinder
  • deepwater riser

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