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Modelling Active Heave Compensation in Ansys AQWA

    • Mohamed Hassan

      Dear Sir/Madam,

      I am trying to model active heave compensation system in Ansys AQWA. The model is consisted of floating vessel lifting wind turbine generator assembly prior to mating it above the foundation. As the installation process is from a floating vessel and not jack up, compensation of heave motion is essential. I am not sure which type of connection will suits best this problem in AQWA.

      Looking forward for your response,

      Best Regards,

      Mohamed Hassan

    • Mike Pettit
      Ansys Employee


      The best approach for modelling active heave compensation is to use Aqwa's user-defined force (UDF) functionality. This allows you to connect the time domain Aqwa solver to a Python server, which calls a Python function at each computational time-step. The solver passes the structure COG position and velocity at that time-step to the Python function, and this returns the forces/moments that should be applied by the solver for that time-step at each structure's COG.

      The Python server code is provided, along with some example UDFs, in your Ansys installation: e.g. C:\Program Files\ANSYS Inc\v231\aqwa\utils\ExternalForceCalculation. You can code the Python function to do anything you like, as long as the additional forces/moments can be determined as a function of the structure's COG position and velocity.

      I'm afraid I can't provide any other coded examples beyond those available in the Ansys installation, but I'm happy to answer any other questions you might have.

      Cheers, Mike

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