Wind generation problems using Turbsim.

[fbelli997]

Hi everyone,

I'm having some trouble simulating wind fields using TurbSim, and I was hoping to get your insights.

I'm generating wind files for different wind speeds and turbulence intensity levels. The issue is that when I compute the turbulence intensity from the .dat files generated by TurbSim, I consistently get lower TI values than what I specified in the input. In some cases the discrepancy is small (around 0.7–0.8%), but in others the error is more significant.

I'm attaching both:

• one of the .inp files I'm using
• an Excel file summarizing the results across all wind conditions:

valutazione_vento.xlsx

Here is how I'm calculating the time step for each case:

    dt_low = ((C_meander * D_wake) / (10 * ws)) / 2.5;
    dt_low_adjusted = floor(dt_low / 0.2) * 0.2;

and here a plot of the PSD of the wind at 7 m/s.

Furthermore, I tried to decrease the dt_low but with poor results. some of the cases reached very good performance, with a loss in accuracy around 0.7/0.8%, while the others keep more or less constant the loss.

Here the input file:

---------TurbSim v2.00.* Input File------------------------
for user-defined time series input
---------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)
True 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)
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-----------------------
31 NumGrid_Z - Vertical grid-point matrix dimension
101 NumGrid_Y - Horizontal grid-point matrix dimension
2.80 TimeStep - Time step [seconds]
2748.00 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")
230 HubHt - Hub height [m] (should be > 0.5GridHeight)
450 GridHeight - Grid height [m]
1500 GridWidth - Grid width(3.2) [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")
"-----" UserFile - Name of the file that contains inputs for user-defined spectra or time series inputs (used only for "USRINP" and "TIMESR" models)
1 IECstandard - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. "1-Ed2") )
15.00 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]
"PL" 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" [-]
155 RefHt - Height of the reference velocity (URef) [m]
7.00 URef - Mean (total) velocity at the reference height [m/s] (or "default" for JET velocity profile)
350 ZJetMax - Jet height [m] (used only for JET velocity profile, valid 70-490 m)
"0.00" PLExp - Power law exponent [-] (or "default")
"0.011" 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----------------------------
"IEC" SCMod1 - u-component coherence model ("GENERAL","IEC","API","NONE", or "default")
"IEC" SCMod2 - v-component coherence model ("GENERAL","IEC","NONE", or "default")
"IEC" SCMod3 - w-component coherence model ("GENERAL","IEC","NONE", or "default")
"12, 3.5273e-4" InCDec1 - u-component coherence parameters for general or IEC models [-, m^-1] (e.g. "10.0 0.3e-3" in quotes) (or "default")
"12, 3.5273e-4" InCDec2 - v-component coherence parameters for general or IEC models [-, m^-1] (e.g. "10.0 0.3e-3" in quotes) (or "default")
"12, 3.5273e-4" InCDec3 - w-component coherence parameters for general or IEC models [-, m^-1] (e.g. "10.0 0.3e-3" in quotes) (or "default")
0 CohExp - Coherence exponent for general model [-] (or "default")

--------Coherent Turbulence Scaling Parameters-------------------
".\EventData" CTEventPath - Name of the path where event data files are located
"les" 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.)
10 CTStartTime - Minimum start time for coherent structures in RootName.cts [seconds]

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

[jjonkman]

Dear @fbelli997,

When ScaleIEC is set to zero in TurbSim, the turbulence intensity calculated by TurbSim will generally be less than expected due to the numerical way TurbSim generates the full field inflow from the underlying spectrum. For more information, see a similar question answered in my post dated June 24, 2024 in the following topic on our forum: https://forums.nrel.gov/t/iec-61400-1-2019-for-turbulence-intensity-in-turbsim/2588.

Best regards,

[fbelli997]

Dear Jason,

Thank you for your kind response.

I’ve resolved the issue regarding the turbulence intensity at hub height setting ScaleIEC=1. However, I’ve noticed that when the turbulence intensity exceeds 0.06, both the wind speed and turbulence intensity fields appear less smooth compared to the results obtained at lower TI values.

Do you think this behavior is correct, or could it be due to a mistake in my implementation? I’m wondering whether this reduced smoothness is to be expected.

I’ve attached some pictures showing the wind speed and turbulence intensity fields at 10 m/s for both 3% and 25% TI.

Thank you in advance.
Best regards,
Federico

[jjonkman]

Dear @fbelli997,

What do you mean by "less smooth"? What specifically is your concern?

Best regards,

[fbelli997]

Dear Jason,

Looking at the figures I shared, both the wind speed and the turbulence intensity appear less uniform across the domain when the turbulence intensity is higher. Do you think this is it correct, or could I be making some mistakes in the setup?

Thank you again for your support

Best regards,

[jjonkman]

Dear @fbelli997,

I would say this is expected.

Best regards,

[fbelli997]

Ok, thank you very much for your help

[fbelli997]

Hi @jjonkman,

I was able to solve the issue I previously faced with the non-uniform wind field outside the wake by setting the IEC scale to 2 and ensuring that both simulation and post-processing durations matched the TurbSim-generated time. To remove the initial transient, I ran simulations for twice the TurbSim duration and processed only the second half.

However, I've now encountered a new issue. When the simulation reaches around 4000 seconds, it consistently crashes for all tested wind speeds. The error is:

Time: 4112 of 10692 seconds. Estimated final completion at 20:04:57.

T1:FARM_UpdateStates:FWrap_Increment:FAST_Solution:FAST_UpdateStates:FAST_AdvanceStates:SolveOptio
n2c_Inp2AD_SrvD:InflowWind_CalcOutput:CalculateOutput:IfW_FlowField_GetVelAcc:Grid4DField_GetVel:O
utside the grid bounds: ( -12.03, 0.00, 150.00)
InflowWind_CalcOutput:InflowWind_GetRotorSpatialAverage:IfW_FlowField_GetVelAcc:Grid4DField_GetVel
:Outside the grid bounds: ( -14.19, 43.55, 80.41)
InflowWind_CalcOutput:InflowWind_GetHubValues:IfW_FlowField_GetVelAcc:Grid4DField_GetVel:Outside
the grid bounds: ( -14.19, 0.00, 149.77)
FAST_AdvanceStates:AD_UpdateStates:AD_CalcWind:AD_CalcWindRotor:IfW_FlowField_GetVelAcc:Grid4DFiel
d_GetVel:Outside the grid bounds: ( -14.19, 0.00, 149.77)

It seems that the wake travels upstream and outside the defined grid. I inspected the last generated VTK files before the crash, and here are the results for two cases (3 m/s and 6 m/s, both with 5% turbulence intensity):

As visible, the wake appears discontinuous in both cases.
Below are the relevant grid settings for the 6 m/s simulation:

--- AMBIENT WIND: INFLOWWIND MODULE --- [used only for Mod_AmbWind=2 or 3]
3.2 DT_Low Time step for low-resolution wind data interpolation; will be used as the global FAST.Farm time step (s) [>0.0]
0.20 DT_High Time step for high-resolution wind data interpolation (s) [>0.0]
127.0 NX_Low Number of low-resolution spatial nodes in X direction for wind data interpolation (-) [>=2]
101.0 NY_Low Number of low-resolution spatial nodes in Y direction for wind data interpolation (-) [>=2]
31.0 NZ_Low Number of low-resolution spatial nodes in Z direction for wind data interpolation (-) [>=2]
0.0 X0_Low Origin of low-resolution spatial nodes in X direction for wind data interpolation (m)
-750.0 Y0_Low Origin of low-resolution spatial nodes in Y direction for wind data interpolation (m)
5.0 Z0_Low Origin of low-resolution spatial nodes in Z direction for wind data interpolation (m)
30.0 dX_Low Spacing of low-resolution spatial nodes in X direction for wind data interpolation (m) [>0.0]
15.0 dY_Low Spacing of low-resolution spatial nodes in Y direction for wind data interpolation (m) [>0.0]s
15.0 dZ_Low Spacing of low-resolution spatial nodes in Z direction for wind data interpolation (m) [>0.0]
57.0 NX_High Number of high-resolution spatial nodes in X direction for wind data interpolation (-) [>=2]
57.0 NY_High Number of high-resolution spatial nodes in Y direction for wind data interpolation (-) [>=2]
87 NZ_High Number of high-resolution spatial nodes in Z direction for wind data interpolation (-) [>=2]
"inflow\inflowfile6mps_0.05.dat" InflowFile - Name of file containing InflowWind module input parameters (quoted string)
--- WIND TURBINES ---
1 NumTurbines Number of wind turbines (-) [>=1] [last 6 columns below used only for Mod_AmbWind=2 or 3]
WT_X WT_Y WT_Z WT_FASTInFile X0_High Y0_High Z0_High dX_High dY_High dZ_High
(m) (m) (m) (string) (m) (m) (m) (m) (m) (m)
400.0 0.0 0.0 "..\FAST4_TUSCANY\6mps-0.05ti-0.88tilt-20.00yaw.fst" 260.0 -140.0 5.0 5.0 5.0 5.0
--- WAKE DYNAMICS ---
1 Mod_Wake - Switch between wake formulations {1:Polar, 2:Curl, 3:Cartesian} (-) (switch)
240 RotorDiamRef - Reference turbine rotor diameter for wake calculations (m) [>0.0]
5 dr - Radial increment of radial finite-difference grid (m) [>0.0]
73 NumRadii - Number of radii in the radial finite-difference grid (-) [>=2]
284 NumPlanes - Number of wake planes (-) [>=2]
0.01 f_c - Cutoff (corner) frequency of the low-pass time-filter for the wake advection, deflection, and meandering model [recommended=1.28*U0/R] (Hz) [>0.0] or DEFAULT [DEFAULT=12.5/R, R estimated from dr and NumRadii, not recommended]
DEFAULT C_HWkDfl_O - Calibrated parameter in the correction for wake deflection defining the horizontal offset at the rotor (m ) or DEFAULT [DEFAULT= 0.0 ]
DEFAULT C_HWkDfl_OY - Calibrated parameter in the correction for wake deflection defining the horizontal offset at the rotor scaled with yaw error (m/deg) or DEFAULT [DEFAULT= 0.0 if Mod_Wake is 2, 0.3 otherwise]
DEFAULT C_HWkDfl_x - Calibrated parameter in the correction for wake deflection defining the horizontal offset scaled with downstream distance (- ) or DEFAULT [DEFAULT= 0.0 ]
DEFAULT C_HWkDfl_xY - Calibrated parameter in the correction for wake deflection defining the horizontal offset scaled with downstream distance and yaw error (1/deg) or DEFAULT [DEFAULT= 0.0 if Mod_Wake is 2, -0.004 otherwise]
DEFAULT C_NearWake - Calibrated parameter for the near-wake correction (-) [>1.0 and <2.5] or DEFAULT [DEFAULT=1.8]
DEFAULT k_vAmb - Calibrated parameters for the influence of the ambient turbulence in the eddy viscosity (set of 5 parameters: k, FMin, DMin, DMax, Exp) (-) [>=0.0, >=0.0 and <=1.0, >=0.0, >DMin, >=0.0] or DEFAULT [DEFAULT=0.05, 1.0, 0.0, 1.0, 0.01]
DEFAULT k_vShr - Calibrated parameters for the influence of the shear layer in the eddy viscosity (set of 5 parameters: k, FMin, DMin, DMax, Exp) (-) [>=0.0, >=0.0 and <=1.0, >=0.0, >DMin, >=0.0] or DEFAULT [DEFAULT=0.016, 0.2, 3.0, 25.0, 0.1]
DEFAULT Mod_WakeDiam - Wake diameter calculation model (-) (switch) {1: rotor diameter, 2: velocity based, 3: mass-flux based, 4: momentum-flux based} or DEFAULT [DEFAULT=1]
DEFAULT C_WakeDiam - Calibrated parameter for wake diameter calculation (-) [>0.0 and <0.99] or DEFAULT [DEFAULT=0.95] [unused for Mod_WakeDiam=1]
DEFAULT Mod_Meander - Spatial filter model for wake meandering (-) (switch) {1: uniform, 2: truncated jinc, 3: windowed jinc} or DEFAULT [DEFAULT=3]
2.1 C_Meander - Calibrated parameter for wake meandering (-) [>=1.0] or DEFAULT [DEFAULT=1.9]

Do you have any insights into what might be causing this issue?
Thanks in advance for your help.

Best regards,
Federico

[jjonkman]

Dear @fbelli997,

Well, I'm guessing the error from IfW_FlowField_GetVelAcc:Grid4DField_GetVel regarding "Outside the grid bounds" is unrelated to the gaps in the wake shown in your visualization. The former is what is terminating your simulation, not the latter.

The latter is likely the result of large thrust variations as the rotor operates in turbulence, which would strengthen and weaken the wake over time.

I'm not sure what is causing former "Outside the grid bounds" error; certainly the reported (X,Y,Z) coordinates (in a coordinate system local to turbine T1) appear to be within the bounds of your high-resolution domains. This suggests to me that something is off in in time, not space, but it is hard for me to guess what the problem is. Can you share the full message written to the command prompt when you execute FAST.Farm?

Best regards,

[fbelli997]

Dear Jason,

this is what I receive in the command prompt when I run the simulation:

FAST.Farm-v4.0.0
Compile Info:

• Compiler: Intel(R) Fortran Compiler 2021
• Architecture: 64 bit
• Precision: single
• OpenMP: No
• Date: Jan 03 2025
• Time: 11:34:41
  Execution Info:
• Date: 05/16/2025
• Time: 08:51:28+0200

Heading of the FAST.Farm input file:
Two turbines with shared moorings
Wake-Added Turbulence (WAT): coefficients:
k_c f_min D_min D_max e
k_Def 0.600 0.000 0.000 2.000 1.000
k_Grad 3.000 0.000 0.000 12.000 0.650

Reading HAWC wind files with grids of 512 x 512 x 64 points (2555 m wide, 2.5 m to 317.5 m
above ground) with a characteristic wind speed of 1 m/s.
Running AWAE.
Running InflowWind.

Reading a 101x31 grid (1500 m wide, 5 m to 455 m above ground) with a characteristic wind
speed of 3 m/s. This full-field file was generated by TurbSim (v2.00.08a-bjj, 18-Jul-2017) on
06-May-2025 at 10:29:19.

Processed 810 time steps of 0.15152-Hz grid-field data (period of 5346 seconds).
Running WakeDynamics.
Running FASTWrapper.
Running OpenFAST.
OpenFAST input file heading:
IEA 15 MW offshore reference model on UMaine VolturnUS-S semi-submersible floating platform

Running ElastoDyn.
Nodal outputs section of ElastoDyn input file not found or improperly formatted.
Running InflowWind.
Running AeroDyn.
AD15 Nodal Outputs: Nodal output section of AeroDyn input file not found or improperly formatted.
Skipping nodal outputs.
AeroDyn: projMod: 2
Projection: Polar, BEM: polar (3D), MomentumCorrection
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 1, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 2, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 4, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 5, blade 1)
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 1, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 2, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 4, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 5, blade 2)
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 1, blade 3)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 2, blade 3)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 4, blade 3)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 5, blade 3)
Running ServoDyn.
Running ServoDyn Interface for Bladed Controllers (using Intel Visual Fortran for Windows).
Using legacy Bladed DLL interface.

FAST_InitializeAll:ED_Init:ED_ReadInput:ReadBladeInputs:ReadBladeFile:The ElastoDyn Blade file,
C:\FFNN\FAST4_TUSCANY..\FAST4_TUSCANY\IEA-15-240-RWT_ElastoDyn_blade.dat, DISTRIBUTED BLADE
PROPERTIES table contains the PitchAxis column. This column is unused and will be removed in
future releases
FAST_InitializeAll:AD_Init:ReadInputFiles:Blade1:ReadBladeInputs:BlCrvAng will be calculated and
overwrite the values specified in blade file
"C:\FFNN\FAST4_TUSCANY..\FAST4_TUSCANY\IEA-15-240-RWT_AeroDyn_blade.dat".
ReadInputFiles:Blade2:ReadBladeInputs:BlCrvAng will be calculated and overwrite the values
specified in blade file "C:\FFNN\FAST4_TUSCANY..\FAST4_TUSCANY\IEA-15-240-RWT_AeroDyn_blade.dat".
ReadInputFiles:Blade3:ReadBladeInputs:BlCrvAng will be calculated and overwrite the values
specified in blade file "C:\FFNN\FAST4_TUSCANY..\FAST4_TUSCANY\IEA-15-240-RWT_AeroDyn_blade.dat".

---

Running ROSCO-v2.9.0
A wind turbine controller framework for public use in the scientific field
Developed in collaboration: National Renewable Energy Laboratory
Delft University of Technology, The Netherlands

T1:FARM_UpdateStates:FWrap_Increment:FAST_Solution:FAST_UpdateStates:FAST_AdvanceStates:AD_UpdateS
tates:BEMT_UpdateStates(node 1, blade 1):ComputeTau:Rotor-averaged axial induction factor is
greater than 0.5; limiting time-varying tau1. This message will not be repeated though the
condition may persist.
FAST_UpdateStates:CalcOutputs_And_SolveForInputs:SolveOption2:AD_CalcOutput:RotCalcOutput:BEMT_Cal
cOutput(node 3, blade 1):UA_CalcOutput:UA_BlendSteady:Temporarily turning off UA due to high
angle of attack or low relative velocity. This warning will not be repeated though the condition
may persist.
Time: 53 of 10692 seconds. Estimated final completion at 09:46:30.

and before to crash I have many of this messages:

FARM_CalcOutput:AWAE_CalcOutput:LowResGridCalcOutput:The center of wake plane #159 for turbine #1
has passed the upper-most Z boundary of the low-resolution domain.
LowResGridCalcOutput:The center of wake plane #160 for turbine #1 has passed the upper-most Z
boundary of the low-resolution domain.
LowResGridCalcOutput:The center of wake plane #161 for turbine #1 has passed the upper-most Z
boundary of the low-resolution domain.
LowResGridCalcOutput:The center of wake plane #162 for turbine #1 has passed the upper-most Z
boundary of the low-resolution domain.
LowResGridCalcOutput:The center of wake plane #163 for turbine #1 has passed the upper-most Z
boundary of the low-resolution domain.
LowResGridCalcOutput:The center of wake plane #164 for turbine #1 has passed the upper-most Z
boundary of the low-resolution domain.
LowResGridCalcOutput:The center of wake plane #165 for turbine #1 has passed the upper-most Z
boundary of the low-resolution domain.
LowResGridCalcOutput:The center of wake plane #166 for turbin
Time: 4112 of 10692 seconds. Estimated final completion at 10:02:18.

T1:FARM_UpdateStates:FWrap_Increment:FAST_Solution:FAST_UpdateStates:FAST_AdvanceStates:SolveOptio
n2c_Inp2AD_SrvD:InflowWind_CalcOutput:CalculateOutput:IfW_FlowField_GetVelAcc:Grid4DField_GetVel:O
utside the grid bounds: ( -12.03, 0.00, 150.00)
InflowWind_CalcOutput:InflowWind_GetRotorSpatialAverage:IfW_FlowField_GetVelAcc:Grid4DField_GetVel
:Outside the grid bounds: ( -41.32, -81.20, 150.19)
InflowWind_CalcOutput:InflowWind_GetHubValues:IfW_FlowField_GetVelAcc:Grid4DField_GetVel:Outside
the grid bounds: ( -13.45, -4.19, 149.78)
FAST_AdvanceStates:AD_UpdateStates:AD_CalcWind:AD_CalcWindRotor:IfW_FlowField_GetVelAcc:Grid4DFiel
d_GetVel:Outside the grid bounds: ( -13.45, -4.19, 149.78)

Aborting FAST.Farm.

PS C:\Users\Utente>

Thank you in advance.

Federico

[jjonkman]

Dear @fbelli997,

Thanks for clarifying. From the information, you've shared, you appear to be using Mod_AmbWind = 2 (single TurbSim file) instead of the recommended Mod_AmbWind = 3 (multiple TurbSim files) option of FAST.Farm. I'm not sure, but I'm guessing there is some numerical round-off happening within FAST.Farm when it is extracting a portion of the TurbSim data for use in the high-resolution domain long into the simulation when using Mod_AmbWind = 2.

That said, we generally recommend using Mod_AmbWind = 3 when using TurbSim to generate inflow for FAST.Farm. So, rather than trying to isolate and fix the bug, it is likely preferential for you to upgrade to Mod_AmbWind = 3. Moreover, to set up the associated wind generation and corresponding spatial-temporal discretization of FAST.Farm to follow of the FAST.Farm modeling guidance, we generally recommend using the Python scripts available within the OpenFAST Toolbox (https://github.com/OpenFAST/openfast_toolbox/tree/main/openfast_toolbox/fastfarm).

Best regards,