Calculation Speed of the Turbsim

Hi, I just use the Turbsim to generate the .wnd file for my simulation, but it looks like that the calculation speed is very slow, is it normally like that or abnormal?

TurbSim Input File. Valid for TurbSim v1.50; 17-May-2010; Example file that can be used with simulations for the NREL 5MW Baseline Turbine; note that UsableTime has been decreased in this file so that the file distributed with the FAST CertTest isn’t as large

---------Runtime Options-----------------------------------
13428 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)
False WrADFF - Output full-field time-series data in TurbSim/AeroDyn form? (Generates RootName.bts)
True 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
0.05 TimeStep - Time step [seconds]
630.0 AnalysisTime - Length of analysis time series [seconds]
600.0 UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds) [bjj: was 630]
90.0 HubHt - Hub height [m] (should be > 0.5GridHeight)
145.0 GridHeight - Grid height [m]
145.0 GridWidth - Grid width [m] (should be >= 2
0 VFlowAng - Vertical mean flow (uptilt) angle [degrees]
-8 HFlowAng - Horizontal mean flow (skew) angle [degrees]

--------Meteorological Boundary Conditions-------------------
IECKAI TurbModel - Turbulence model (“IECKAI”=Kaimal, “IECVKM”=von Karman, “GP_LLJ”, “NWTCUP”, “SMOOTH”, “WF_UPW”, “WF_07D”, “WF_14D”, or “NONE”)
“1-ed2” IECstandard - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. “1-Ed2”) )
“B” IECturbc - IEC turbulence characteristic (“A”, “B”, “C” or the turbulence intensity in percent) (“KHTEST” option with NWTCUP, 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]
PL WindProfileType - Wind profile type (“JET”=Low-level jet,“LOG”=Logarithmic,“PL”=Power law, or “default”, or “USR”=User-defined)
90. RefHt - Height of the reference wind speed [m]
18.0 URef - Mean (total) wind speed at the reference height [m/s]
default ZJetMax - Jet height [m] (used only for JET wind 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/s)^2] (or “default”)
default PC_UV - Hub mean u’v’ Reynolds stress [(m/s)^2] (or “default”)
default PC_VW - Hub mean v’w’ Reynolds stress [(m/s)^2] (or “default”)
default IncDec1 - u-component coherence parameters (e.g. “10.0 0.3e-3” in quotes) (or “default”)
default IncDec2 - v-component coherence parameters (e.g. “10.0 0.3e-3” in quotes) (or “default”)
default IncDec3 - w-component coherence parameters (e.g. “10.0 0.3e-3” in quotes) (or “default”)
default CohExp - Coherence exponent (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 (“random”, “les” or “dns”)
true Randomize - Randomize disturbance scale and location? (true/false)
1.0 DistScl - Disturbance scale (ratio of dataset height to rotor disk).
0.5 CTLy - Fractional location of tower centerline from right (looking downwind) to left side of the dataset.
0.5 CTLz - Fractional location of hub height from the bottom of the dataset.
10.0 CTStartTime - Minimum start time for coherent structures in RootName.cts [seconds]

NOTE: Do not add or remove any lines in this file!

Hi Deyi.Fu,

I recently run Turbsim (to create a .bts file) with following parameters:
35 Vertical grid-point matrix dimension
101 Horizontal grid-point matrix dimension
0.10 Time step [seconds]
200.0 Analysis time [seconds]

In my case, it took 6 hours. I also wonder how NREL will respond your question.

I will try to compile OpenFAST with single precision and try again. Maybe that will quicken it. (Before, I used the Turbsim that came directly with OpenFAST compilation which was in double precision).

Best regards,

Here is a link to an older topic that discusses the CPU time expected with TurbSim simulations: TurbSim CPU Times. Keep in mind that I was using a slower computer 12 years ago. :grinning: The relationship between the number of grid points and the CPU time should hold, but the actual times will vary. Also, if your simulation requires more memory than your computer has available, your CPU times will suffer. You can calculate the approximate memory requirements here: Memory Requirements for full-field wind arrays

@Salur.Basbug: I do not see any reason for you to use a double-precision version of TurbSim. The wind speeds that are generated have random phases and are ultimately truncated to about 3 decimal places of precision, so computing the velocities in double-precision will slow down the process and use more memory without creating any more accuracy.

A 64-bit version of TurbSim will allow you to compute larger grids (i.e., use more memory) than a 32-bit version, but this is different than using double-precision vs single-precision arithmetic. (Note: I’m making this distinction here because many people get the addressing scheme and precision of arithmetic confused.) If you are using the Windows version distributed with the latest OpenFAST release, that is a 64-bit single-precision arithmetic version.

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Thanks a lot @Bonnie.Jonkman for the reply and the links, will be very useful :slight_smile:

Best regards,