Dear all,

Is it possible to run simulations with the NREL15MW new turbine without using any SubDyn data as it was onshore? I have been doing that with DTU10MW until now without any problems, but now I am having some issues with this new turbine.

The message that appears is the next one:

FFWind_CalcOutput [position=(-0.16947, 0.29429, -5.58670E-02) in wind-file coordinates]: FF wind
array boundaries violated. Grid too small in Z direction (height (Z=-5.58670E-02 m) is below the
grid and no tower points are defined)”

At the beginning the message was showing a positive value for Z coordinate, which has been solved updating my TurbSim archive, but now…I cannot understand why I need to have my grid defined under Z=0m if there is nothing there (apart that this makes nosense)
If I try to run the same case but adding the SubDyn.dat, I do not have any issues to run the simulation, which means that the substructure is necessary, but I do not get why.

Can be that without the substructure, the WTG suffers an abnormal deflection?

I would appreciate any kind of help, thank you in advanced,

Gonzalo Ahedo

Dear Gonzalo,

When you disabled SubDyn, did you also disable the platform degrees of freedom in ElastoDyn (PtfmSurge = False, etc.)? If not, the turbine will fall (due to gravity) and there will be no substructure to react to motion of the tower base / platform; disabling the platform will cantilever the tower to the ground / inertial frame.

FYI: Disabling SubDyn will change the boundary condition of the tower, and thus, likely require a change to the tower mode shapes in ElastoDyn.

Best regards,

Dear Jason,

Thank you for your quick reply. You were right, I was forgetting to disable platform’s DOF-s and the tower+turbine were falling due to gravity.

Thank you too for the reminder of modifying the tower configuration, really useful.

Best regards,

Gonzalo Ahedo