help for Hydrodyn.

DEAR Jonkman

I am so sorry to bother you again.
I have been researching the improvement of floating platform recently and have encountered a little difficulty.
I made some modifications based on existing semi-submersible platforms(“OO-Star”).The hydrodynamic coefficients (.hst,.1,.3 files) needed for FAST are obtained through Sesam , but I don’t know how to set the viscous force in hydrodyn to match the plateform which is designed by myself.
Specifically, how are these parameters determined in the picture? Although I have read the DTU-10RWT report, I still can’t fully understand it.I hope you can give me some advice or help.

Best regards to you.


Dear Long.Gao,

I’m not familiar with the report or floating platform you are modeling to comment specifically. How are the viscous effects described for the floater you are trying to model in OpenFAST?

The platform addition stiffness and damping can often be set to zero; they can be used to calibrate a model to a known response if the actual coefficients of stiffness and damping are unknown. For viscous effects, it is typically better to specify the effects through the strip-theory solution (in terms of joints, members, and drag coefficients) rather than through the platform addition damping.

Best regards,

Dear Jonkman

Thanks for you kindly reply and helpful advice. Maybe I have known How to continue my project .

Thank you again.

Best regards,