Verification of the new FAST v8 Capabilities for the Modeling of Fixed-Bottom Offshore Wind Turbines

Braulio Barahona, Jason Jonkman, Rick Damiani, Amy Robertson, Greg Hayman

Research output: Contribution to conferencePaperpeer-review

3 Scopus Citations


Coupled dynamic analysis has an important role in the design of offshore wind turbines because the systems are subject to complex operating conditions from the combined action of waves and wind. The aero-hydro-servo-elastic tool FAST v8 is framed in a novel modularization scheme that facilitates such analysis. Here, we present the verification of new capabilities of FAST v8 to model fixed-bottom offshore wind turbines. We analyze a series of load cases with both wind and wave loads and compare the results against those from the previous international code comparison projects-the International Energy Agency (IEA) Wind Task 23 Subtask 2 Offshore Code Comparison Collaboration (OC3) and the IEA Wind Task 30 OC3 Continued (OC4) projects. The verification is performed using the NREL 5-MW reference turbine supported by monopile, tripod, and jacket substructures. The substructure structural-dynamics models are built within the new SubDyn module of FAST v8, which uses a linear finite-element beam model with Craig-Bampton dynamic system reduction. This allows the modal properties of the substructure to be synthesized and coupled to hydrodynamic loads and tower dynamics. The hydrodynamic loads are calculated using a new strip theory approach for multimember substructures in the updated HydroDyn module of FAST v8. These modules are linked to the rest of FAST through the new coupling scheme involving mapping between module-independent spatial discretizations and a numerically rigorous implicit solver. The results show that the new structural dynamics, hydrodynamics, and coupled solutions compare well to the results from the previous code comparison projects.

Original languageAmerican English
Number of pages15
StatePublished - 2015
Event33rd Wind Energy Symposium 2015 - Kissimmee, United States
Duration: 5 Jan 20159 Jan 2015


Conference33rd Wind Energy Symposium 2015
Country/TerritoryUnited States

Bibliographical note

See NREL/CP-5000-63067 for preprint

NREL Publication Number

  • NREL/CP-5000-64955


  • FAST8
  • fixed-bottom offshore wind
  • model verification


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