FF wind array

[jimmygasser]

Hello, I have an issue running the 5MW test. I need to change the wind direction, which I did by changing the PropagationDir in InflowWind.dat. By just putting 0.1 or anything else, I then get the error :

" Reading a 101x35 grid (1000 m wide, 5 m to 345 m above ground) with a characteristic wind speed of 9.243 m/s. This full-field file was generated by TurbSim (from OpenFAST-v3.0.0-98-g7bde6b54) on 14-Sep-2021 at 11:37:08.

Processed 2000 time steps of 10-Hz full-field data (period of 200 seconds).

Farm_Initialize:Farm_ValidateInput:OutFmt produces a column width of 10 instead of 20 characters. Farm_Initialize:For efficiency, NumPlanes has been reduced to the number of time steps (134). Farm_Initialize:AWAE_Init:AWAE_UpdateStates:InflowWind_CalcOutput:CalcOutput:IfW_FFWind_CalcOutput [position=(2980.8, 552.11, 345) in wind-file coordinates]: FF wind array boundaries violated: Grid too small in Y direction. Y=552.11; Y boundaries = [-500, 500]

"

which, if I'm correct, means that my wind goes outside of the Turbsim wind domain (which is unlimited in X, -500 to 500 in Y and up to 340 in Z). However, even when I try to change that in the 90m_08mps.inp input file (by putting for example 2000 for GridWidth instead of 1000), and I run it again, the exact same error occurs (and the grid size (in bold in the error message) is still the same.... I've spent days trying different combinations both in the TurbSim input file and the FASTFarm input file, trying to follow the modelling guidance, but cannot manage to get over this issue.

I do not really get it, how can I make my TurbSim array larger..?

[jjonkman]

Dear @jimmygasser,

I cannot see how FAST.Farm would say the grid width is 1000 m if your TurbSim simulation uses 2000 m. Are you sure you specifying the correct TurbSim file in InflowWind when running FAST.Farm?

That said, when using Amb_ModWind = 2 or 3 in FAST.Farm, the FAST.Farm documentation recommends against changing the PropagationDir in InflowWind different from 0, +/-190, or 180 degrees. This is to avoid having the FAST.Farm wind domain different from the TurbSim domain, such that interpolation of the wind data, and subsequent smoothing out of the turbulent inflow, would occur. See the online FAST.Farm documentation for more information: https://openfast.readthedocs.io/en/main/source/user/fast.farm/InputFiles.html#ambient-wind-with-inflowwind-module-input-files.

Best regards,

[jimmygasser]

Thank you for your quick answer !

I believe the issue came from the fact that I changed the .inp file of Turbsim, but did not run Turbsim so the .bts file did not update as well (I thought the update would happen automatically when running FAST.Farm.exe). Anyway, it works now !

So if I am correct, what I should do to change the wind direction in my wind farm, has more to do with the turbines' positions/orientations within the farm, while keeping a wind along the X-axis (or Y...). Is this right ?

[jjonkman]

Dear @jimmygasser,

When using TurbSim to generate the ambient wind inflow for FAST.Farm, I agree that it is recommend to change the positions/orientations of the wind turbines to simulate different wind directions than to change InflowWind input PropagationDir.

Best regards,