How to specify the GuyanDampSize??

Hello!!!

I am studying the SubDyn model. I checked the file “NRELOffshrBsline5MW_OC3Tripod_SubDyn.dat” and observed that you did specify the 6x6 damping matrix (GuyanDampSize). My questions are as below.

  1. how did you identify these values?

  2. Is this matrix the damping of the whole system excluding the aerodynamic damping and hydrodynamic damping?

Thank you so much in advance.

Dear Danupon,

The 6x6 Guyan damping matrix is used to specify the damping matrix of the 6 Guyan modes of the substructure; this would typically be used to represent structural damping. The (3,3) value for the OC3-Tripod model was specified following the guidance documented in the SubDyn User’s Guide and Theory Manual: openfast.readthedocs.io/en/main … e-coupling. This guidance was first written when the Guyan damping matrix was not an input to SubDyn, so, Add AddCLin in HydroDyn could be used instead. Now that the Guyan damping matrix is an input to SubDyn, you can now specify this damping in SubDyn instead of in HydroDyn.

Best regards,

Thank you so much for your reply.