Multi-body PotFile for shared mooring systems in FAST.Farm

Wind & Water Computer-Aided Engineering Software Tools
1

Hello, everyone!

I’m setting up a FAST.Farm case with a shared anchor/mooring system between floating turbines and want to confirm the correct HydroDyn PotFile configuration.

  1. Should I regenerate the potential-flow solution with NBody set to the number of platforms (keeping NBodyMod = 1) to capture hydrodynamic interaction (radiation/diffraction coupling) between the floaters?
  2. Or can I reuse a single-body PotFile (NBody = NBodyMod = 1) originally generated for an individually-moored turbine, relying on MoorDyn to capture the shared-mooring coupling while accepting that hydrodynamic cross-body interaction is neglected?

Is hydrodynamic multi-body interaction handled independently from mooring-line coupling in FAST.Farm — i.e., can a shared-mooring array still use single-body potential-flow data as a valid simplification, or is a multi-body PotFile required for physically consistent results?

Besides, since I don’t have the access to WAMIT, could I use ANSYS AQWA and BEMRosetta to generate multi-body Potfile?

Best regards,

Jingyi

2

Dear @Jingyi.Wu

The way FAST.Farm is set up now, it is not possible to have hydrodynamic interaction between floating platforms modeled in distinct instances of OpenFAST for each turbine. So (2) is correct.

In general, I would say guess that the hydrodynamic interaction would be negligible unless the floaters are very closely spaced, which is not likely given the desire to have sizeable spacing between rotors in a wind farm, e.g., beyond 5D spacing. This is why FAST.Farm is set up the way it is.

FYI: In FAST.Farm currently, interaction between turbines occurs through wake effects, a farm-wide super controller (when enabled), and through shared mooring systems (when enabled).

Best regards,

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