Dear Dr. Jason Jonkman
I am thankful for your help and sorry to bother you once again. Until now i was using only strip-theory in the HydroDyn, however now to better match the RAO i have to use Potential flow model only. I followed the HydroDyn user’s guide and theory manual to understand properly the methodology of using Potential flow model only. I set the “PotMod = 1” to enable the WAMIT. Following the Section 6.8 (Floating platform) of HydroDyn manual which says that “for a potential-flow-only model do not create any strip theory joints or members in the input file”. I made all the hydrodynamic coefficients zero and removed all the member joints and members etc. when i run the analysis it gives me an error and aborted. The error was:
“FAST_InitializeAll:HydroDyn_Init: Both meshes must be committed before they can be mapped.
HydroDyn_Init: Both meshes must be committed before they can be mapped.”
I searched on this forum to find any help regarding this error and fortunately found your kind response to one of the user, given as
(Link: Foundation Stiffness and damping in FAST v8 - #11 by Patrick.Quasten)
“Dear Patrick,
I was able to reproduce your error when I set up a similar model myself. It appears that there is a bug in HydroDyn preventing it from functioning properly when a model has no strip-theory nodes (NJoints = NMembers = 0). We’ll fix this in a future release of HydroDyn. In the meantime, I suggest that you set up your HydroDyn module with two joints and one member, but with all member properties and coefficients set to zero.”
I followed your suggestion and made NJoints = 2 and NMembers = 1, with all the properties equal to 0. But the error i got was
“A member can not have zero length.”
I also tried it by assigning small length e.g. 0.5 and run it but then the error i obtain was “MDivSize must be greater than zero”.
I will be highly thankful for your time and your help.