Free decay tests

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Free decay tests

Postby Florence.Haudin » Tue Nov 05, 2019 4:00 am

Good morning,
I would like to know if there is among the examples provided for openfast, an example of free decay tests for a semi submersible or another platform?
I guess that the user has to implement himself the AddCLin matrix taken into account the mooring configuration/parameters?

Thanks in advance.
Best regards.
Florence Haudin.

Posts: 4338
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO

Re: Free decay tests

Postby Jason.Jonkman » Thu Nov 07, 2019 10:52 am

Dear Florence,

No, none of the example simulations provided with FAST are for a free-decay test, but such a simulation is quite simple to set up. Normally free-decay tests are performed without wind or wave excitation (CompInflow=0 and most likely CompAero=0 in the FAST primary input file, and WaveMod=0 in the HydroDyn input file). Enable whichever degrees of freedom you want (most certainly the platform DOFs) and set a nonzero initial platform displacement. You shouldn't need to set AddCLin for the mooring system; instead you can enable one of the mooring modules.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
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