Questions about wind data created in TurbSim

Thank you for all your help.

I have two questions.

  1. How to set GridHeight?
    I am currently creating wind data acting on a wind turbine with a hub height of 60m and a rotor diameter of about 75m. The manual says that the GridHeight should be set to at least 10% of the rotor diameter. I want the wind loads to act on the entire tower as well, so I set the GridHeight to 119.9m. Is this correct?

  2. How to set WrADTWR and Tower data points
    If I set WrADTWR to True, I get the following warning.
    CreateGrid: There are no extra tower data points below the grid. Tower output will be turned off.
    How do I set the tower data points?

Supplement to the above.
Wind data created in TurbSim will be used in OpenFAST.

An example of input data is shown below.

---------Runtime Options-----------------------------------
True Echo - Echo input data to .ech (flag)
321654 RandSeed1 - First random seed (-2147483648 to 2147483647)
“RANLUX” RandSeed2 - Second random seed (-2147483648 to 2147483647) for intrinsic pRNG, or an alternative pRNG: “RanLux” or “RNSNLW”
True WrBHHTP - Output hub-height turbulence parameters in binary form? (Generates RootName.bin)
True WrFHHTP - Output hub-height turbulence parameters in formatted form? (Generates RootName.dat)
True WrADHH - Output hub-height time-series data in AeroDyn form? (Generates RootName.hh)
True WrADFF - Output full-field time-series data in TurbSim/AeroDyn form? (Generates RootName.bts)
False WrBLFF - Output full-field time-series data in BLADED/AeroDyn form? (Generates RootName.wnd)
True WrADTWR - Output tower time-series data? (Generates RootName.twr)
True WrFMTFF - Output full-field time-series data in formatted (readable) form? (Generates RootName.u, RootName.v, RootName.w)
False WrACT - Output coherent turbulence time steps in AeroDyn form? (Generates RootName.cts)
False Clockwise - Clockwise rotation looking downwind? (used only for full-field binary files - not necessary for AeroDyn)
0 ScaleIEC - Scale IEC turbulence models to exact target standard deviation? [0=no additional scaling; 1=use hub scale uniformly; 2=use individual scales]

--------Turbine/Model Specifications-----------------------
39 NumGrid_Z - Vertical grid-point matrix dimension
39 NumGrid_Y - Horizontal grid-point matrix dimension
0.05 TimeStep - Time step [seconds]
800 AnalysisTime - Length of analysis time series [seconds] (program will add time if necessary: AnalysisTime = MAX(AnalysisTime, UsableTime+GridWidth/MeanHHWS) )
“ALL” UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds unless UsableTime is “ALL”)
60.00 HubHt - Hub height [m] (should be > 0.5GridHeight)
119.90 GridHeight - Grid height [m]
119.90 GridWidth - Grid width [m] (should be >= 2
0 VFlowAng - Vertical mean flow (uptilt) angle [degrees]
0 HFlowAng - Horizontal mean flow (skew) angle [degrees]

--------Meteorological Boundary Conditions-------------------
“IECKAI” TurbModel - Turbulence model (“IECKAI”,“IECVKM”,“GP_LLJ”,“NWTCUP”,“SMOOTH”,“WF_UPW”,“WF_07D”,“WF_14D”,“TIDAL”,“API”,“USRINP”,“TIMESR”, or “NONE”)
“unused” UserFile - Name of the file that contains inputs for user-defined spectra or time series inputs (used only for “USRINP” and “TIMESR” models)
“1-ed2” IECstandard - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. “1-Ed2”) )
“A” IECturbc - IEC turbulence characteristic (“A”, “B”, “C” or the turbulence intensity in percent) (“KHTEST” option with NWTCUP model, not used for other models)
“NTM” IEC_WindType - IEC turbulence type (“NTM”=normal, “xETM”=extreme turbulence, “xEWM1”=extreme 1-year wind, “xEWM50”=extreme 50-year wind, where x=wind turbine class 1, 2, or 3)
“default” ETMc - IEC Extreme Turbulence Model “c” parameter [m/s]
“default” WindProfileType - Velocity profile type (“LOG”;“PL”=power law;“JET”;“H2L”=Log law for TIDAL model;“API”;“USR”;“TS”;“IEC”=PL on rotor disk, LOG elsewhere; or “default”)
“unused” ProfileFile - Name of the file that contains input profiles for WindProfileType=“USR” and/or TurbModel=“USRVKM” [-]
60.00 RefHt - Height of the reference velocity (URef) [m]
13 URef - Mean (total) velocity at the reference height [m/s] (or “default” for JET velocity profile) [must be 1-hr mean for API model; otherwise is the mean over AnalysisTime seconds]
70.0 ZJetMax - Jet height [m] (used only for JET velocity profile, valid 70-490 m)
“default” PLExp - Power law exponent [-] (or “default”)
“default” Z0 - Surface roughness length [m] (or “default”)

--------Non-IEC Meteorological Boundary Conditions------------
“default” Latitude - Site latitude [degrees] (or “default”)
0.05 RICH_NO - Gradient Richardson number [-]
“default” UStar - Friction or shear velocity [m/s] (or “default”)
“default” ZI - Mixing layer depth [m] (or “default”)
“default” PC_UW - Hub mean u’w’ Reynolds stress [m^2/s^2] (or “default” or “none”)
“default” PC_UV - Hub mean u’v’ Reynolds stress [m^2/s^2] (or “default” or “none”)
“default” PC_VW - Hub mean v’w’ Reynolds stress [m^2/s^2] (or “default” or “none”)

--------Spatial Coherence Parameters----------------------------
“default” SCMod1 - u-component coherence model (“GENERAL”,“IEC”,“API”,“NONE”, or “default”)
“default” SCMod2 - v-component coherence model (“GENERAL”,“IEC”,“NONE”, or “default”)
“default” SCMod3 - w-component coherence model (“GENERAL”,“IEC”,“NONE”, or “default”)
“default” InCDec1 - u-component coherence parameters for general or IEC models [-, m^-1] (e.g. “10.0 0.3e-3” in quotes) (or “default”)
“default” InCDec2 - v-component coherence parameters for general or IEC models [-, m^-1] (e.g. “10.0 0.3e-3” in quotes) (or “default”)
“default” InCDec3 - w-component coherence parameters for general or IEC models [-, m^-1] (e.g. “10.0 0.3e-3” in quotes) (or “default”)
“default” CohExp - Coherence exponent for general model [-] (or “default”)

--------Coherent Turbulence Scaling Parameters-------------------
“M:\coh_events\eventdata” CTEventPath - Name of the path where event data files are located
“Random” CTEventFile - Type of event files (“LES”, “DNS”, or “RANDOM”)
true Randomize - Randomize the disturbance scale and locations? (true/false)
1 DistScl - Disturbance scale [-] (ratio of event dataset height to rotor disk). (Ignored when Randomize = true.)
0.5 CTLy - Fractional location of tower centerline from right [-] (looking downwind) to left side of the dataset. (Ignored when Randomize = true.)
0.5 CTLz - Fractional location of hub height from the bottom of the dataset. [-] (Ignored when Randomize = true.)
30 CTStartTime - Minimum start time for coherent structures in RootName.cts [seconds]

Dear @Yosuke.Matsumoto,

Regarding (2), you are getting the warning from CreateGrid when WrADTWR = TRUE because your grid already extends down nearly to ground level.

Your grid seems to be sufficient as is, but wider than you need. I would refer to the TurbSim documentation for information on how to set GridHeight and GridWidth, particularly the text around Figure 5:

Best regards,

Thanks for the reply.

By shortening the GridWidth, the warning text no longer appears.
On the other hand, I believe that in order for the wind load to act on the tower, the grid needs to be set near the ground surface. For example, if we follow the manual and set the rotor diameter to 1.1 times the 75m rotor diameter, this would be approximately 83m. In this case, the wind will not act on the tower within 18.5 m(60-83/2) of the ground surface .
If you want to obtain a more accurate wind load acting on the tower, it would be better to set the grid to near the ground surface. What do you think?

Dear @Yosuke.Matsumoto,

I agree. TurbSim allows two options for generating wind for the tower. Either set GridHeight > GridWidth (the middle of Figure 5 from the TurbSim manual) or set WrADTWR = TRUE (Figure 4)

Best regards,

Thanks for the reply.

Based on your advice, I have made the following calculations However, it failed.

  1. set GridHeight > GridWidth
    60.00 HubHt
    119.9 GridHeight
    83.0 GridWidth
    CreateGrid:The lowest grid point (-18.4 m) must be above the ground. Adjust the appropriate values in the input file.

60.00 HubHt
83.0 GridHeight
83.0 GridWidth
As shown by the orange line in the figure, no profile was generated in the section 18.5 m GL from the ground surface. Note that the blue line in the figure is the result of the calculation with GridHeight=GridWidth =119.9 m. Note that these results were plotted with pyDatView after reading the bts file.

Based on these results, I thought it would be better to calculate GridHeight=GridWidth =119.9 m, although the grid size will be larger.

Dear @Yosuke.Matsumoto,

Regarding (1), with HubHt = 60 m and GridWidth = 83 m, the maximum possible GridHeight (to ensure that grid points are not below the ground) is HubHt + GridWidth/2 = 101.5 m (technically, TurbSim will require GridHeight < 101.5 because grid points are not allowed at ground level).

Regarding (2), I’m not sure pyDatView supports post-processing of the TurbSim tower file, but the InflowWind module of OpenFAST should make use of it.

Best regards,