NWTC

Dear Bartosz, By a *.wnd file, presumably you are referring to the InflowWind module's uniform wind file type (WindType = 2). These files are time varying, but spatially uniform (they may include shear). Such files are typically used for deterministic IEC wind cases like gusts and direction changes....

Dear Jiaping, Yes, the FAST.Farm User's Guide and Theory Manuel has now been finalized and published. Here: https://www.nrel.gov/docs/fy21osti/78485.pdf. Dear Hamid, The FAST.Farm source code now fully supports the functional super controller. And the super controller interface is documented in the ...

Dear Ricardo, I would say the answer depends on what you are trying to model in reality. Are you trying to mimic what a nacelle-mounted anemometer would measure (in the near wake of the rotor and boundary layer of the nacelle)? Then placing the wind measurement as you have sounds correct. (Usually y...

Dear Tianhui, The geometry of the OC3-monopile is quite simple; and the joints and members are defined in the SubDyn input file (4 joints, 3 members, extending from -20.0001 m to 10 m above SWL). The output members and nodes are defined in the MEMBER OUTPUT LIST in the SubDyn input file. In the OC3 ...

Dear Tianhui, I'm not sure I understand your question. Are you asking what output member α (Mα) and output node β (Nβ) mean in SubDyn? These are described in the SubDyn documentation. Regardless, most offshore wind turbines in OpenFAST are modeled with the tower in ElastoDyn and the substructure in ...

Dear Andre, The MassDen in MoorDyn is the mass (not weight) per unit length of the mooring line. This mass density should be expressed independent from external buoyancy. The line weight in water will be calculated by subtracting the line buoyancy from the mass times gravity. I hope that helps. Best...

Dear Andre, These large skew angle and low TSR errors imply to me that the motion of the rotor is large enough that it meets or exceeds the wind velocity, which sounds extreme, but would mean the flow through the rotor can drop to near zero and the skew angle can be large. Can you confirm that the t...

Dear Younes, Nice video :-). From the plots, it looks like the turbine and/or controller of T2 are not reacting as expected when the wake from T1 hits T2. The error you are receiving seems to be triggered by the large (and negative) generator speed. I gather you are using the OpenFAST model of NREL ...

Dear Tianhui,

I'm afraid I can't answer your question regarding the impact of ice velocity on the ice load output from IceDyn. This would be a better question for the developers (Prof. Dale Karr et al) at the University of Michigan, who I don't believe follow this forum.

Best regards,

Dear Bartosz, I would expect the Cp surface to be independent of wind speed when the rotor is rigid. For a flexible rotor, different wind speeds can result in different Cp surfaces, depending on how flexible the blades are. If the results are not too different, then using the Cp surface for the rigi...

Dear Younes, FAST.Farm will throw this error when the rotor thrust is so high that the near-wake correction model is no longer valid. I expect that the downstream turbine (T2) is not operating as expected if the thrust is this high. Is 268 s, when the error is triggered, the time when the wake from ...

Dear Tianhui, The effect of the ice loading on the tower-top acceleration and displacement will depend on the rigidity of the monopile. (If the monopile were rigid, there would be no effect of monopile loading at the tower top). It looks like the ice load has a very minor effect on the tower-top acc...

Dear Bartosz,

A similar question regarding GenDOF in ElastoDyn was asked and answered here: viewtopic.php?f=30&t=1110&p=4798.

Best regards,

Dear Bartosz,

I'm not seeing anything out of the ordinary with these results.

Best regards,

Dear Bartosz, The aerodynamic loads on the rotor will include a torque, which will tend to induce roll/sway of the floater. There will also be gyroscopic loads from the spinning rotor, which mainly induce yaw, but when the rotor is tilted (due to shaft tilt or floater heal), could also induce roll. ...