NWTC

Dear Jason, I am sorry for the confusion. Could you please help to check the attached two documents when you get a chance: 1. Please change source p-y.txt to source p-y.xlsx file. Inside this Excel document, the first sheet (dense sand (p-y)) is to pre-calculate soil resistance p = a*tanh(b*X(1) at ...

Dear Lingling, The UserTwrLd() routine of FAST v7 requires that you return the load (per unit length) at the tower node that is passed to the routine (separately for each node). The global displacement (X,Y,Z) and rotation (about X,Y,Z, assuming small angles) of the node are passed to the routine. ...

Dear all, If I want to incorporate p-y curve in the UserTwrLd subroutine, do I have to specify the resistance (p) equation related to displacement (y) just right at the TwrNode position where the displacement vector is calculated? Did somebody have such examples to share with me? I don't know whethe...

Dear Jason,

I agree with you!

Really appreciate!

Dear Jason, I was thinking the high natural frequencies of platform may be introduced by the last distributed spring at the pile bottom. And since there is no mass specified for the platform, the natural frequencies of them are quite high. From the comparison of natural frequencies of tower reported...

Dear Jason, I have the platform natural frequencies of surge or sway at around 8 Hz. And I have the platform natural frequencies of roll or pitch around 39 Hz. I just couldn't understand the physical meaning of these four natural frequencies and why they are too high. In my model, I don't have any p...

Have you solved your problem?

Maybe try to increase the tolerance or decrease the time step.

Dear Jason, I have some questions: 1. Can SubDyn be used to incorporate the pile-soil interaction? 2. In FAST, if I use the distributed spring model to model the soil effect do I have to turn on all the 6 platform DoFs in time domain simulation since I encounter the same warning as discussed above. ...

Dear Jason,

Really appreciate!

No problem at all in other normal conditions! I just want to take a look of the pitch sensitivity of this rotor. I may skip this angle for time being!

Best regards,

Dear Marshall, Really appreciate! Did you also have troubles when running with SNL 13.2 MW rotor? I have tried the initial azimuth as 60 and 90 but the blade deflections are still as high as 50 meters. Do you have some other suggestions? When will the FAST with BeamDyn be published? Looking forward ...

Dear Jason,

Really appreciate.

I am running the 13.2 MW rotor developed by SNL. I was thinking this is due to the flexibility of this long blade as you posted before.

Best regards,

Dear Jason, I have run the NREL 5MW turbine with monopile rigid foundation model with a fixed pitch angle 50 deg. There was a small deflection violated warning but the results seem like reasonable. Then I have run a 13.2 MW offshore wind turbine model with a 50 deg pitch angle. There was also a smal...

Dear Jason,

Really appreciate!

Best regards,

Dear Jason,

Really appreciate!

Now the questions are clear, but the results still deviate some. I have DT = 0.00125 and I don't know whether this would yeild some difference. I have attached the simulation file, could you please take a look of it?

Thanks and best regards,

Dear Jason, Really appreciate! I have the following problems to discuss with you: 1. I have used the tower.dat file run with my compiled FAST.exe. If I only turned on DoFs of tower (8 DoFs in total), I have obtained the first two natural frequencies as 0.2260, 0.2380. If I turn on all the DoFs in FA...