The Effect of Second-Order Hydrodynamics on Floating Offshore Wind Turbines

Line Roald, Jason Jonkman, Amy Robertson, Ndaona Chokani

Research output: Contribution to journalArticlepeer-review

112 Scopus Citations


Offshore winds are generally stronger and more consistent than winds on land, making the offshore environment attractive for wind energy development. A large part of the offshore wind resource is however located in deep water, where floating turbines are the only economical way of harvesting the energy. The design of offshore floating wind turbines relies on the use of modeling tools that can simulate the entire coupled system behaviour. At present, most of these tools include only first-order hydrodynamic theory. However, observations of supposed second-order hydrodynamic responses in wave-tank tests performed by the DeepCwind consortium suggest that second-order effects might be critical. In this paper, the methodology used by the oil and gas industry has been modified to apply to the analysis of floating wind turbines, and is used to assess the effect of second-order hydrodynamics on floating offshore wind turbines. The method relies on combined use of the frequency-domain tool WAMIT and the timedomain tool FAST. The proposed assessment method has been applied to two different floating wind concepts, a spar and a tension-leg-platform (TLP), both supporting the NREL 5-MW baseline wind turbine. Results showing the hydrodynamic forces and motion response for these systems are presented and analysed, and compared to aerodynamic effects.

Original languageAmerican English
Pages (from-to)253-264
Number of pages12
JournalEnergy Procedia
StatePublished - 2013
Event10th Deep Sea Offshore Wind R and D Conference, DeepWind 2013 - Trondheim, Norway
Duration: 24 Jan 201325 Jan 2013

Bibliographical note

See NREL/CP-5000-58718 for preprint

NREL Publication Number

  • NREL/JA-5000-60504


  • offshore floating wind turbine
  • second-order hydrodynamics
  • spar buoy
  • tension-leg platform
  • wave loads


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