Rotational inertia of the fluid ballast

Dear Jason,

I’m wondering how FAST considering the rotational inertia of the fluid ballast in members. I have read the HydroDyn Manual, in which gives the instruction that rotational inertia of the fluid in the member is ignored (please see section 4.3.14 (page 24) of the manual). Does it mean this part of rotational inertia should be included in the “PtfmRIner” and “PtfmYIner” (one of the input in the ElastoDyn file) ?

Dear Shengtao,

Yes, I agree that you could augment PtfmRIner, PtfmPIner, and PtfmYIner with the missing inertia terms, if they are important. More information on this limitation is given in my Jul 11, 2014 post in the following forum topic: http://forums.nrel.gov/t/addclin-for-oc4-semisubmersible/944/3.

Best regards,