Problem in changing version from 3.5 to 4 in FASTfarm on a SCALED WIND TURBINE MODEL

[fbelli997]

Hi everyone,

I'm trying to convert a scaled wind turbine model from FAST.Farm version 3.5 to version 4.0 using polar wake model.

My scripts work fine with steady wind (InflowWind mode = 1), but when I switch to mode = 2 (Step Wind), I get the following error:

Heading of the FAST.Farm input file:
FAST.Farm input - file, using two turbines separated by 3D downstream and an
offset of 30m, with a turbulent inflow given by one turbsim box
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 (18.396 m wide, 1.80000E-02 m to
2.286 m above ground) with a characteristic wind speed of 1 m/s.
Running AWAE.
Running InflowWind.

Farm_Initialize:AWAE_Init:InflowWind_Init:IfW_UniformWind_Init: Could not read upflow column in
uniform wind files. Assuming upflow is 0.
AWAE_Init:Could not allocate memory for u%xhat_plane.

I'm actually using 110 planes, and the grid is defined as follow:

0.025 DT_Low Time step for low-resolution wind data interpolation; will be used as the global FAST.Farm time step (s) [>0.0]
0.025 DT_High Time step for high-resolution wind data interpolation (s) [>0.0]
81 NX_Low Number of low-resolution spatial nodes in X direction for wind data interpolation (-) [>=2]
71 NY_Low Number of low-resolution spatial nodes in Y direction for wind data interpolation (-) [>=2]
41 NZ_Low Number of low-resolution spatial nodes in Z direction for wind data interpolation (-) [>=2]
0 X0_Low Origin of low-resolution spatial nodes in X direction for wind data interpolation (m)
-3.5 Y0_Low Origin of low-resolution spatial nodes in Y direction for wind data interpolation (m)
0.015 Z0_Low Origin of low-resolution spatial nodes in Z direction for wind data interpolation (m). In this way the hub is coincident with the grid.
0.25 dX_Low Spacing of low-resolution spatial nodes in X direction for wind data interpolation (m) [>0.0]
0.1 dY_Low Spacing of low-resolution spatial nodes in Y direction for wind data interpolation (m) [>0.0]
0.1 dZ_Low Spacing of low-resolution spatial nodes in Z direction for wind data interpolation (m) [>0.0]
31 NX_High Number of high-resolution spatial nodes in X direction for wind data interpolation (-) [>=2]
31 NY_High Number of high-resolution spatial nodes in Y direction for wind data interpolation (-) [>=2]
30 NZ_High Number of high-resolution spatial nodes in Z direction for wind data interpolation (-) [>=2]

Instead when i change to 3 for running the bts file, the error changes in this:

Heading of the FAST.Farm input file:
FAST.Farm input - file, using two turbines separated by 3D downstream and an
offset of 30m, with a turbulent inflow given by one turbsim box
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 (18.396 m wide, 1.80000E-02 m to
2.286 m above ground) with a characteristic wind speed of 1 m/s.
Running AWAE.
Running InflowWind.

Reading a 71x41 grid (7 m wide, 1.50003E-02 m to 4.015 m above ground) with a characteristic
wind speed of 4.3004 m/s. This full-field file was generated by TurbSim (v2.00.08a-bjj,
18-Jul-2017) on 29-May-2025 at 15:55:08.

Processed 1870 time steps of 40-Hz grid-field data (period of 46.75 seconds).

Farm_Initialize:AWAE_Init:AWAE_UpdateStates:InflowWind_CalcOutput:InflowWind_GetRotorSpatialAverag
e:IfW_FlowField_GetVelAcc:Grid3DField_GetCell: G3D wind array boundaries violated. Grid too small
in Z direction (height (Z=6.92815E-03 m) is below the grid and no tower points are defined).

The .bts file was generated with ZBottom = 0.015 m, and it worked without issues in FAST.Farm version 3.5.
Do you know what could be causing these errors in version 4.0?

Do you know what is the source of the error?

Thanks in advance!

[jjonkman]

Dear @fbelli997,

Regarding your first error, I'm not sure. Can you run this same case (with WindType = 2) in FAST.Farm v3.5?

Regarding your second error, it sounds like you have an aerodynamic analysis node that extends below your TurbSim grid. Are you low- and high-resolution domains in FAST.Farm aligned with your TurbSim domain?

Best regards,

[jjonkman]

Dear @fbelli997,

Can you clarify what you mean when you say that "the simulation stops without given any error"? What is written to the command prompt after executing FAST.Farm? If there is an issue with input file processing, what is written to the echo file when Echo = TRUE?

Best regards,

[fbelli997]

Dear Jason,

Here below the command prompt message after the execution of the program:

Microsoft Windows [Versione 10.0.22631.4037]
(c) Microsoft Corporation. Tutti i diritti riservati.

C:\Users\fbell>C:\neural_networks\NN_main_folder\WTM12_3WT-Polar_4th\FAST4.exe C:\neural_networks\NN_main_folder\WTM12_3WT-Polar_4th\FAST_Farm_0_20.fstf

**************************************************************************************************
FAST.Farm

Copyright (C) 2025 National Renewable Energy Laboratory
Copyright (C) 2025 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.
**************************************************************************************************

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: 06/05/2025
 - Time: 16:00:22+0200

 Heading of the FAST.Farm input file:
   FAST.Farm     input         - file, using two turbines separated by 3D downstream and an
   offset of 30m, with a turbulent inflow given by one turbsim box
C:\Users\fbell>

Using the two lines:

0.15, 1.0, 0.0, 1.0, 0.01        k_vAmb        Calibrated parameter for the influence of ambient turbulence in the eddy viscosity (-) [>=0.0] or DEFAULT [=0.05] FEDE 0.15
0.016, 0.2, 3.0, 25.0, 0.1      k_vShr        Calibrated parameter for the influence of the shear layer in the eddy viscosity (-) [>=0.0] or DEFAULT [=0.016] DEFAULT  FEDE 0.016              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]

If I change the 5 values for both the 2 lines in "DEFAULT" the simulation starts correctly.

Thank you in advance.
best regards.

[jjonkman]

Dear @fbelli997,

If there is an issue with input file processing, I suggest enabling Echo and see what is written to the echo file.

Best regards,

[PierDG]

I've also been getting the 'AWAE_Init:Could not allocate memory for u%xhat_plane.' error when trying to run windtype=2, no matter how much I decrease the grid size or the number of planes I still keep getting the same error and it works just fine with other wind types. At first I thought it was a matter of bad sintax in the scripts or the time series I've been using but now I'm pretty sure those are fine and I'm lost. I've tried only on the latest version and not on FAST.Farm v3.5. Has anyone else had the same problem as us? If so, does anyone know what could possibly be causing this issue?

[andrew-platt]

I'm not sure I have an answer to the AWAE_Init:Could not allocate memory for u%xhat_plane issue. I notice you are using version 4.0.0. Could you try with version 4.0.5 - there are some fixes for memory issues in FAST.Farm included between 4.0.0 and 4.0.5 (mostly related to OpenMP though). If 4.0.5 shows this same issues, then let me know and we can take a look at it in more detail.

V4.0.5 uses the same exact input files as v4.0.0, so updating to it should be relatively simple (https://github.com/openFAST/openfast/releases/v4.0.5 - we don't have executables yet. V4.0.4 also contains the bugfixes: executables here: https://github.com/openFAST/openfast/releases/v4.0.4).

Regards,