NREL 5MW monopile OWT modelling details

Wind & Water General
4

Dear Dhaneesh,

Here are my answers to your questions:

  1. In FAST v7, the entire support structure (monopile + tower) is modeled together via the tower-bending DOFs. The 20 tower nodes you refer to (TwrNodes = 20) are equally spaced elements (with nodes located at the centers of the elements) from the seabed (assuming you’ve set TwrDraft > 0 in the platform file) to the tower top. Whichever of these elements/nodes are below the water level will be used for the hydrodynamic load calculation. Increasing TwrNodes will improve the hydrodynamic discretization. Please note that the discretization approach has changed drastically in FAST v8 and OpenFAST.

  2. I agree with your commentary, but I’m not sure I understand your question.

Best regards,