Dear Mr Jonkman,
My Bachelor exam deals with modeling a turbine-soil interaction with FAST. I recieved a running version of a 10MW Onshore Wind Turbine which I transferred to an OffshoreWT already.
Now, after finishing the calculations with a fixed towerbase at the mudline, I want to model the turbine-soil interaction with varieties of soil layers and stiffness parameters (those of OC3 studies) to evaluate the influence of the soil parameters on the OWT’s eigenfrequencies by analysing them.
The running model is based on FAST v.8 and I’ve already read a lot about the difficulties modeling the soil. Transferring the whole model to FAST v.7 (which could model a distributed spring model as I read) seems a little costly at the first glance, isn’t it? (1)
Another opportunity I read was to use FAST v.8 and HydroDyn only with platform additional stiffness and damping to imitate a soil layer. But here we’d just model 1 soil layer and no water, right? (2)
Then I read that there is a SubDyn upgrade upcoming, which supports linear coupled springs foundations. When could that preanounced update be available? (3)
The last option seems to be the Apparent Fixity like described here: AeroDyn Feedback (dialogue with Athanasios Kontis)
So this method can be useful to get different values for the mode shapes for different soil parameters, did I understand that correctly? (4)
What would you recommend me to do? One of my tasks is also to model aero- and hydrodynamic loads on the turbine with embedded monopile foundation. This is also possible in FAST v.8 through the AF model, isn’t it? (5)
Thank You all for this valueable forum, I’m really greatful!
Best Regards,