turbsim inflow wind

[Bq2181]

OpenFAST

Copyright (C) 2023 National Renewable Energy Laboratory
Copyright (C) 2023 Envision Energy USA LTD

This program is licensed under Apache License Version 2.0 and comes with ABSOLUTELY NO WARRANTY.
See the "LICENSE" file distributed with this software for details.

---

OpenFAST-Unversioned from 6b8706b
Compile Info:

• Compiler: Intel(R) Fortran Compiler 2021
• Architecture: 64 bit
• Precision: single
• OpenMP: No
• Date: Oct 08 2023
• Time: 20:01:15
  Execution Info:
• Date: 04/18/2024
• Time: 16:15:49+0800

OpenFAST input file heading:
FAST Certification Test #22: NREL 5.0 MW Baseline Wind Turbine with ITI Barge Configuration,
for use in offshore analysis

Running ElastoDyn.
Nodal outputs section of ElastoDyn input file not found or improperly formatted.
Running InflowWind.

Reading a 13x13 grid (80 m wide, 44.288 m to 124.29 m above ground) with a characteristic wind
speed of 18.2 m/s. This full-field file was generated by TurbSim (v2.00.07a-bjj, 14-Jun-2016)
on 18-Apr-2024 at 14:38:13.

Processed 4000 time steps of 20-Hz grid-field data (period of 200 seconds).
Running HydroDyn.
Setting WaveTMax to 0.0 since WaveMod = 0
Reading in WAMIT output with root name ".../5MW_Baseline/HydroData/Barge".
Computing radiation impulse response functions and wave diffraction forces.
Running MoorDyn (v2.0.0, 2022-12-08).
This is MoorDyn v2, with significant input file changes from v1.
Copyright: (C) 2022 National Renewable Energy Laboratory, (C) 2019 Matt Hall
Parsing MoorDyn input file: .\NRELOffshrBsline5MW_ITIBarge4_MoorDyn.dat
Created mooring system: 8 lines, 16 points, 0 rods, 0 bodies.
Finalizing initial conditions using dynamic relaxation.
t=54 FairTen 1: 2.70238E+05, 2.69922E+05, 2.69364E+05
Fairlead tensions converged to 1% after 54 seconds.
MoorDyn initialization completed.
Running ServoDyn.
Time: 0 of 200 seconds.

FAST_Solution0:CalcOutputs_And_SolveForInputs:SolveOption2:SolveOption2c_Inp2AD_SrvD:InflowWind_Ca
lcOutput:InflowWind_GetSpatialAverage:CalculateOutput:IfW_FlowField_GetVelAcc:Grid3DField_GetCell:
GF wind array boundaries violated: Grid too small in Y direction. Y=-40.454; Y boundaries = [-40,
40]

OpenFAST encountered an error during simulation initialization.
Simulation error level: FATAL ERROR

Aborting OpenFAST.

D:\app\OpenFast\r-test-main\glue-codes\openfast\5MW_ITIBarge_DLL_WTurb_WavesIrr>

[Bq2181]

When I tried to use turbulent wind generated by turbsim in openfast, I kept making this mistake. Do you know how to solve it?

[jjonkman]

Dear @Bq2181,

Similar questions have been asked before. All aerodynamic analysis nodes within the AeroDyn aerodynamics module of OpenFAST (including any rotor and tower points) must reside within the wind domain for the full length of the simulation, including taking into account floating platform motion and turbine deflection. In your case, the NREL 5-MW baseline rotor is 126-m in diameter while your TurbSim domain is a box with a width and height of 80 m.

Best regards,

[dorsamgh]

Dear @jjonkman,

I have an issue with the wind file generated by TurbSim. I used to run simulations for the 15 MW semi-submersible model using a wind file with a speed of 11 m/s without any errors. However, after making some changes to the OpenFAST source code and building a new version, I encountered the following error during the simulation:

Reading a 31x31 grid (246 m wide, 3 m to 273 m above ground) with a characteristic wind speed of 11 m/s. This full-field file was generated by TurbSim (v1.50, 25-Sep-2009) on 24-Apr-2024 at 15:41:22.
.
.
.
.
FAST_Solution:FAST_AdvanceStates:SolveOption2c_Inp2AD_SrvD:InflowWind_CalcOutput:CalcOutput
Wind_CalcOutput [position=(72.291, 127.2, 150.33) in wind-file coordinates]: FF wind array boundaries violated: Grid too small in Y direction. Y=127.2; Y boundaries = [-123, 123]

OpenFAST encountered an error at simulation time 540.27 of 750 seconds. Simulation error level: FATAL ERROR

Aborting OpenFAST.

I would like to ask how I should modify the TurbSim parameters to resolve this issue. Should I change the values of NumGrid_Z and NumGrid_Y? The current values of GridWidth and GridHeight are 246 and 270, respectively.

Thank you in advance for your help.

[jjonkman]

Dear @dorsamgh,

OpenFAST is complaining that the GridWidth is not wide enough for the displacements of the aerodynamic analysis nodes you are simulating. So, you should increase GridWidth, rerun TurbSim, and then rerun OpenFAST.

Best regards,

[dorsamgh]

Dear @jjonkman ,
so there is no need to change the NumGrid_Z and NumGrid_Y? and another question, how much should I increase GridWidth?
Does this parameter have a specific limit when increased? Is a value like 300 sufficient?
thank you.

[jjonkman]

NumGrid_Y and NumGrid_Z determine the discretization of the inflow domain whereas GridWidth and GridHeight determine the size of the domain. As states before, the size the inflow domain should be sufficient to avoid aerodynamic analysis nodes leaving the domain as a result of wind turbine displacement/deflection. So, you should estimate the amount of displacement/deflection expected (including floater motion for floating wind turbines) and ensure the domain size is a bit larger than that; a 10% margin is typically sufficient.

The descretization requirements are dictated by convergence of the solution (too coarse of a discretization will result in less turbulence excitation than would be expected). Our rule of thumb is to use a spatial discretization of the inflow domain equal to a the maximum chord of the blade (i.e., NumGrid_Y = GridWidth/MaxChord + 1), but this may be computationally expensive for the IEA Wind 15-MW RWT, especially if you increase the domain size by a lot.

Best regards,