Experimental and numerical studies of the pontoon effect on vortex-induced motions of deep-draft semi-submersibles

Mingyue Liu, Longfei Xiao, Yibo Liang, Longbin Tao

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The vortex-induced motion (VIM) is a critical issue in mooring and riser system design for column-type deepwater platforms. As regards to deep-draft semi-submersibles (DDS), even though VIM is mainly excited by vortex shedding around columns, the large-volume pontoons beneath the columns are also responsible for the wake interference, implying a non-negligible influence on VIM behavior. An experimental study and three-dimensional numerical simulations were performed to analyze the pontoon effect on the VIM of two semi-submersibles and a four-column structure without pontoons. The numerical results using Detached Eddy Simulation (DES) are in good agreement with the experimental measurements obtained from the towing model tests. The present investigations indicate that the resonant phenomenon is observed for all configurations. However, the four-column structure without pontoons shows the most significant transverse responses and yaw motions at both 0°- and 45°-incidences owing to the largest fluctuating lift forces induced by the well-established wake. Additionally, the negative values of work done by the pontoons at all reduced velocities confirm their damping effect on the VIM response.

LanguageEnglish
Pages59-79
Number of pages21
JournalJournal of Fluids and Structures
Volume72
Early online date8 May 2017
DOIs
Publication statusPublished - 31 Jul 2017

Fingerprint

Semisubmersibles
Pontoons
Vortex flow
Mooring
Vortex shedding
Damping
Systems analysis
Computer simulation

Keywords

  • deep-draft semi-submersible
  • experimental study
  • numerical simulation
  • pontoon effect
  • vortex-induced motion

Cite this

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title = "Experimental and numerical studies of the pontoon effect on vortex-induced motions of deep-draft semi-submersibles",
abstract = "The vortex-induced motion (VIM) is a critical issue in mooring and riser system design for column-type deepwater platforms. As regards to deep-draft semi-submersibles (DDS), even though VIM is mainly excited by vortex shedding around columns, the large-volume pontoons beneath the columns are also responsible for the wake interference, implying a non-negligible influence on VIM behavior. An experimental study and three-dimensional numerical simulations were performed to analyze the pontoon effect on the VIM of two semi-submersibles and a four-column structure without pontoons. The numerical results using Detached Eddy Simulation (DES) are in good agreement with the experimental measurements obtained from the towing model tests. The present investigations indicate that the resonant phenomenon is observed for all configurations. However, the four-column structure without pontoons shows the most significant transverse responses and yaw motions at both 0°- and 45°-incidences owing to the largest fluctuating lift forces induced by the well-established wake. Additionally, the negative values of work done by the pontoons at all reduced velocities confirm their damping effect on the VIM response.",
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Experimental and numerical studies of the pontoon effect on vortex-induced motions of deep-draft semi-submersibles. / Liu, Mingyue; Xiao, Longfei; Liang, Yibo; Tao, Longbin.

In: Journal of Fluids and Structures, Vol. 72, 31.07.2017, p. 59-79.

Research output: Contribution to journalArticle

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