Hi @Jason.Jonkman just checking again to see if you have any feedback having seen the wind shear profile.
Thank you.
Regards,
AOAW
Dear @Andre.White,
Your data looks fine, but do you have the rest of the data in this file, including the headers, etc.? Perhaps your windshear.dat file is simply not formatted properly? Have you used the same format as the sample user-defined wind profile file provided in the TurbSim v2.00 archive (https://www.nrel.gov/wind/nwtc/assets/downloads/TurbSim/TurbSim_v2.00.07a-bjj.exe), e.g., UsrShear.profiles?
Best regards,
Hi @Jason.Jonkman:
About the error that I reported above. My hub height is 150 m, when I increase GridHeight from 279.5 m to 280 m I get the error. However, if I only change hub height to 150.005 m, no error occurs. If I want to further increase GridHeight, to say, 290 m, I have to increase hub height to 160 m. However, my hub height is 150 m and so this is somewhat problematic.
Would be grateful for your thoughts on this. I thought if hub height > 0.5GridHeight, that would satisfy the criteria for the model to run successfully. This is not the case based on what has occurred.
Thank you.
Regards,
AOAW
Hi @Jason.Jonkman:
I ran the TurbSim example using the UsrShear.Profiles file. However, I notice that the value computed for the mean wind speed at hub height is lower than the value entered in the TurbSim input file. The value of URef in the TurbSim input file is 18.2 m/s but the value computed using the shear profile is 7.1 m/s. I computed this value by taking the average of Uh over the entire time series. If use the PL profile and enter the value of 18.2 m/s as the URef, the value comes out to 18.2 m/s when I take the average of Uh from the outptu file. Part of the example input file and the shear profile are shown below. I have also attached a part of the related output file.
1) Can you please say why the reference wind speed at Hub Height does not show a value of 18.2 m/s as included in the input file when the shear profiles are used but gives a lower value of 7.1 m/s ? In other words how do I get the reference wind speed at hub height to be a specific value, in this case 18.2 m/s, when I use the shear profile?
2) Also, if I would like to change the coherence exponent in the input file from default to a value can I just remove default and insert specified value.
Thank you.
Regards,
AOAW
Hi @Andre.White,
When WindProfileType = “USR”, TurbSim input URef is not used. Instead, the wind speed at RefHt is derived from the user-specified wind profile in the ProfileFile. When you set WindProfileType = “USR”, I would expect that you’d specify the wind profile across the entire vertical extent of the wind domain (from HubHt-GridHeight/2 to HubHt+GridHeight/2). Please see the TurbSim User’s Guide v2.0 for more information: https://www.nrel.gov/wind/nwtc/assets/downloads/TurbSim/TurbSim_v2.00.pdf.
Best regards,
Thanks @Jason.Jonkman.
I will look at this further.
Regards,
AOAW
@Andre.White, one thing I noticed is that your file header for the profiles you posted 7 days ago indicates that there are only 5 data lines (NumUSRz = 5), whereas it looks like you specified 28 lines. TurbSim will read only NumUSRz lines of the data. I believe that TurbSim uses nearest-neighbor beyond the data listed in the file, so the wind speed for everything above 50 m will be 84 m/s for that file.
Also, could you post the entire TurbSim input file that you are using when you got the access violation error (I believe it is 150m_88mps_wind_shearJCS1r.inp). Access violations usually indicate a programming error or that the program is not robustly checking for potential errors with I/O or memory allocation. In that case, it is most helpful to have the exact settings you used so that we can reproduce the error and track it down.
I know there were some bugs that we fixed in the OpenFAST version of TurbSim that may fix the issue you are seeing with TurbSim v2.00.07a, but I haven’t run your input file with the new version to check.
Hi @Bonnie.Jonkman:
Changing the number of lines in the data solved the problem. I had changed it in a previous wind shear profile file, thought I had used the same base file but that was not the case. So I am now getting the 88.4 m/s as the value for URef.
I have another query though about the spatial coherence parameters. I want to change CohExp to 0.85. The value used in said paper by Amor et al (2020). I simply changed the value from default to 0.85. Do I have to change any of the other parameters (see below), for this to take effect?
--------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”)
0.85 CohExp - Coherence exponent for general model [-] (or “default”)
Thank you.
Regards,
AOAW
Hi @Bonnie.Jonkman:
This is the input data for the TurbSim input file, 150m_88mps_wind_shearJCS1r.inp.
---------TurbSim v2.00.* Input File------------------------
---------Runtime Options-----------------------------------
False Echo - Echo input data to .ech (flag)
1 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”
False WrBHHTP - Output hub-height turbulence parameters in binary form? (Generates RootName.bin)
False WrFHHTP - Output hub-height turbulence parameters in formatted form? (Generates RootName.dat)
False 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)
False WrADTWR - Output tower time-series data? (Generates RootName.twr)
False 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)
True 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-----------------------
31 NumGrid_Z - Vertical grid-point matrix dimension
31 NumGrid_Y - Horizontal grid-point matrix dimension
0.25 TimeStep - Time step [seconds]
3650 AnalysisTime - Length of analysis time series [seconds] (program will add time if necessary: AnalysisTime = MAX(AnalysisTime, UsableTime+GridWidth/MeanHHWS) )
3650 UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds unless UsableTime is “ALL”)
150.005 HubHt - Hub height [m] (should be > 0.5GridHeight)
280 GridHeight - Grid height [m]
750 GridWidth - Grid width [m] (should be >= 2(RotorRadius+ShaftLength))
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-ED3” IECstandard - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. “1-Ed2”) )
7.38 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]
“USR” 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”)
“windshear.dat” ProfileFile - Name of the file that contains input profiles for WindProfileType=“USR” and/or TurbModel=“USRVKM” [-]
150.005 RefHt - Height of the reference velocity (URef) [m]
88.4 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]
“default” 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”)
0.85 CohExp - Coherence exponent for general model [-] (or “default”)
--------Coherent Turbulence Scaling Parameters-------------------
“/home/lkilcher/work/nwtc/turbsim/trunk/Test/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]
====================================================
! NOTE: Do not add or remove any lines in this file!
Regards,
AOAW
Dear @Andre.White,
Regarding the spatial coherence, that is all you should need to do to overwrite the default value. The default values for the other spatial coherence model depend on which spectral model you’ve specified. Again. see the TurbSim User’s Guide v2.0 for more information.
Best regards,
Thanks @Jason.Jonkman. I have seen the information on the other models in the theory manual but just double checking to make sure that is all I need to do.
Regards,
AOAW
Hi @Jason.Jonkman:
So I have rectified the issue with the mean wind speed at hub height being less than what it should be. @Bonnie.Jonkman pointed out an error that I had in the wind shear profile file. After I ran simulation in TurbSim, I used the time series to plot the wind spectrum. The data that I used for wind shear profile came from a paper by Kapoor et al (2020). Although, I got the same mean wind speed at hub height for said profile, I notice that my wind spectrum is not exactly the same as shown in the paper even though is looks like a good fit (my spectrum is the blue on the LHS and the one from the paper is red on the RHS). However, some differences are shown at lower frequencies. I just want to find out if you think there will, any major issue based on this difference given that the wind speed at hub height that I computed was the same, that is 65.8 m/s.
I would be grateful to hear your thoughts on this.
Thank you.
Regards,
AOAw
Dear @Andre.White,
Nothing specifically stands out as a major difference when comparing the spectra this way; that said, it would be easier to compare the spectra if they are both plotted in the same figure and if the data is smoothed (or binned) to reduce noise.
Best regards,
@Jason.Jonkman Noted. Unfortunately, I do not have the original data, so I cannot plot both on same graph.
Regards,
AOAW
Hi @Jason.Jonkman:
In TurbSim I know it is possible to find the mean wind speed at a specific height besides hub height. For example, say hub height (90m) but I would also like to get the mean wind speed at say, 60 m how is that done? I tried by setting the height of reference velocity RefHt, to 60 and ran the simulation. However, what I am having trouble with it to locate the values of the mean wind speed at 60 m. I can locate Hub Height velocities but I don’t know where to find the time series for the mean wind speeds at 60 m. Would be very grateful for your assistance.
Thank you.
Regards,
AOAW
Dear @Andre.White,
You can always compute the time-series average of velocity at any point in the field of the TurbSim grid by extracting the velocity output at that point and taking the time-series mean.
That said, TurbSim superimposes turbulence fluctuations with zero mean on top of the mean profile, so, the mean at any point in the field will simply be the value of the mean profile at that point. And, of course, the mean profile is typically a simple analytical expression (like a power law) or user-defined (as you discussed above) based on the setting of WindProfileType.
Best regards,
Thanks @Jason.Jonkman.
The problem I am really having is to view the data on the full field grid. I used the function,
readfile_BTS.m from the utilities toolbox and that gives me a 4D matrix which is too large to view in MATLAB. It there a simpler way to view the data on the grid?
Regards,
AOAW
Dear @Andre.White,
The 4 dimensions are time (1), the (u,v,w) components (1), and the (Y,Z) coordinates (2). You could eliminate one dimension by only plotting the u component. You could coarsen the remaining data by not viewing every time step or coordinate. You could also plot slices of the domain along a Y or Z axis.
Best regards,
Hi @Jason.Jonkman:
Thank you. I plotted a coarser grid which allowed me to view all of the 4D data. I now understand the data and am able to extract the velocities that I need for the finer grid.
Regards,
AOAW