Abstract
This study presents a computational fluid dynamics (CFD) investigation of vortex-induced motions (VIM) of the INO WINDMOOR floater [1] during towing operations. The simulations were performed at model scale for direct comparison with towing tests of INO WINDMOOR FOWT model previously conducted in SINTEF Ocean’s Ocean Basin [2]. Two towing configurations were examined: one single towing line and towing line with bridles.
The CFD setup includes a free surface and fully coupled six-degree-of-freedom (6DOF) body motion, solved using the overset mesh approach combined with the Improved Delayed Detached-Eddy Simulation (IDDES) turbulence model. The simulations successfully reproduced VIM responses in both configurations and showed encouraging qualitative agreement with experimental observations. In particular, the relative motion trends between the two towing setups were captured correctly, demonstrating the ability of CFD to distinguish which configuration induces larger motion in each DOF.
While some overprediction of amplitudes was observed for certain DOF, the results remain within reasonable bounds and highlight areas for further calibration. The very small free-surface waves observed at low Froude numbers suggest that simplified single-phase simulations may be sufficient for calm-water towing conditions. To explore this, sensitivity tests without the free surface have been initiated, and comparative results will be presented at the conference.
Overall, the study demonstrates the feasibility and potential of using CFD to reproduce VIM phenomena of a FOWT under towing operations. The findings provide valuable insights for future model development, validation, and towing configuration design for floating wind applications.