Issues related to the comparison of wake characteristics among different floating platform types #3154
Description
I would like to ask for some advice on whether my current FAST.Farm wake-model setup is appropriate. I am studying the influence of platform motion characteristics on wake development for a 15 MW floating wind turbine, with a focus on comparing TLP and semi-submersible configurations. I am currently using FAST.Farm and OpenFAST version 4.1.2. One issue I have observed is that, at the beginning of the simulation, the VTK wake outputs consistently contain NaN values, and the wake field only becomes physically reasonable after approximately 700 s. I did not encounter this behavior when running the same setup with the older OpenFAST/FAST.Farm version 3.5.3. In addition, based on my current results, the wake characteristics between the TLP and semi-submersible cases appear to be very similar, despite their clearly different motion responses. At this stage, I am unsure whether this similarity reflects a physically reasonable result or indicates a potential issue with my FAST.Farm configuration. My input parameters were largely defined by following the recommendations and guidelines provided in the FAST.Farm documentation. I would greatly appreciate any feedback or suggestions on whether my wake-model setup is reasonable. Below I list my main FAST.Farm settings for reference:------- FAST.Farm for OpenFAST 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
--- SIMULATION CONTROL ---
True Echo - Echo input data to .ech? (flag)
FATAL AbortLevel - Error level when simulation should abort (string) {"WARNING", "SEVERE", "FATAL"}
3000.0 TMax - Total run time (s) [>=0.0]
2 Mod_AmbWind - Ambient wind model (-) (switch) {1: high-fidelity precursor in VTK format, 2: one InflowWind module, 3: multiple instances of InflowWind module}
2 Mod_WaveField - Wave field handling (-) (switch) {1: use individual HydroDyn inputs without adjustment, 2: adjust wave phases based on turbine offsets from farm origin}
0 Mod_SharedMooring - Shared mooring system model (switch) {0: None, 3=MoorDyn}
--- SHARED MOORING SYSTEM --- [used only for Mod_SharedMoor>0]
"" SharedMoorFile - Name of file containing shared mooring system input parameters (quoted string) [used only when Mod_SharedMooring > 0]
0.01 DT_Mooring - Time step for farm-level mooring coupling with each turbine (s) [used only when Mod_SharedMooring > 0]
True WrMooringVis - Write shared mooring visualization, at the global FAST.Farm time step (-) [only used for Mod_SharedMooring=3]
--- AMBIENT WIND: PRECURSOR IN VTK FORMAT --- [used only for Mod_AmbWind=1]
1.0 DT_Low-VTK - Time step for low -resolution wind data input files; will be used as the global FAST.Farm time step (s) [>0.0]
0.1 DT_High-VTK - Time step for high-resolution wind data input files (s) [>0.0]
"unused" WindFilePath - Path name to VTK wind data files from precursor (string)
False ChkWndFiles - Check all the ambient wind files for data consistency? (flag)
--- AMBIENT WIND: INFLOWWIND MODULE --- [used only for Mod_AmbWind=2 or 3]
0.2 DT_Low - Time step for low -resolution wind data interpolation; will be used as the global FAST.Farm time step (s) [>0.0]
0.1 DT_High - Time step for high-resolution wind data interpolation (s) [>0.0]
401 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]
60 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)
-350 Y0_Low - Origin of low -resolution spatial nodes in Y direction for wind data interpolation (m)
5 Z0_Low - Origin of low -resolution spatial nodes in Z direction for wind data interpolation (m)
10 dX_Low - Spacing of low -resolution spatial nodes in X direction for wind data interpolation (m) [>0.0]
10 dY_Low - Spacing of low -resolution spatial nodes in Y direction for wind data interpolation (m) [>0.0]
10 dZ_Low - Spacing of low -resolution spatial nodes in Z direction for wind data interpolation (m) [>0.0]
61 NX_High - Number of high-resolution spatial nodes in X direction for wind data interpolation (-) [>=2]
61 NY_High - Number of high-resolution spatial nodes in Y direction for wind data interpolation (-) [>=2]
76 NZ_High - Number of high-resolution spatial nodes in Z direction for wind data interpolation (-) [>=2]
"IEA-15-240-RWT_InflowFile.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 "FFTest_WT1.fst" 250 -150.0 5 5 5 5
--- WAKE DYNAMICS ---
2 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]
8 dr - Radial increment of radial finite-difference grid (m) [>0.0]
60 NumRadii - Number of radii in the radial finite-difference grid (-) [>=2]
2000 NumPlanes - Number of wake planes (-) [>=2]
0.2 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]
DEFAULT C_Meander - Calibrated parameter for wake meandering (-) [>=1.0] or DEFAULT [DEFAULT=1.9]
--- CURLED-WAKE PARAMETERS [only used if Mod_Wake=2 or 3] ---
DEFAULT Swirl - Switch to include swirl velocities in wake (-) (switch) [DEFAULT=TRUE]
0 k_VortexDecay - Vortex decay constant for curl (-) [DEFAULT=0.0001]
DEFAULT NumVortices - The number of vortices in the curled wake model (-) [DEFAULT=100]
DEFAULT sigma_D - The width of the vortices in the curled wake model non-dimesionalized by rotor diameter (-) [DEFAULT=0.2]
DEFAULT FilterInit - Switch to filter the initial wake plane deficit and select the number of grid points for the filter {0: no filter, 1: filter of size 1} or DEFAULT [DEFAULT=1] [unused for Mod_Wake=1] (switch)
5 k_vCurl - Calibrated parameter for scaling the eddy viscosity in the curled-wake model (-) [>=0] or DEFAULT [DEFAULT=2.0 ]
DEFAULT Mod_Projection - Switch to select how the wake plane velocity is projected in AWAE {1: keep all components, 2: project against plane normal} or DEFAULT [DEFAULT=1: if Mod_Wake is 1 or 3, or DEFAULT=2: if Mod_Wake is 2] (switch)
--- WAKE-ADDED TURBULENCE ---
1 WAT - Switch between wake-added turbulence box options {0: no wake added turbulence, 1: predefined turbulence box, 2: user defined turbulence box} (switch)
"WAT_MannBoxDB/FFDB_D100_512x512x64.u" WAT_BoxFile - Filepath to the file containing the u-component of the turbulence box (either predefined or user-defined) (quoted string)
512, 512, 64 WAT_NxNyNz - Number of points in the x, y, and z directions of the WAT_BoxFile [used only if WAT=2, derived value if WAT=1] (-)
7.2, 7.2, 7.2 WAT_DxDyDz - Distance (in meters) between points in the x, y, and z directions of the WAT_BoxFile [used only if WAT=2, derived value if WAT=1] (m)
default WAT_ScaleBox - Flag to scale the input turbulence box to zero mean and unit standard deviation at every node [DEFAULT=False] (flag)
default WAT_k_Def - Calibrated parameters for the influence of the maximum wake deficit on wake-added turbulence (set of 5 parameters: k_Def, FMin, DMin, DMax, Exp) (-) [>=0.0, >=0.0 and <=1.0, >=0.0, >DMin, >=0.0] or DEFAULT [DEFAULT=[0.6, 0.0, 0.0, 2.0, 1.0 ]]
default WAT_k_Grad - Calibrated parameters for the influence of the radial velocity gradient of the wake deficit on wake-added turbulence (set of 5 parameters: k_Grad, FMin, DMin, DMax, Exp) (-) [>=0.0, >=0.0 and <=1.0, >=0.0, >DMin, >=0.0] or DEFAULT [DEFAULT=[3.0, 0.0, 0.0, 12.0, 0.65]
--- VISUALIZATION ---
False WrDisWind - Write low- and high-resolution disturbed wind data to .Low.Dis.t.vtk etc.? (flag)
1 NOutDisWindXY - Number of XY planes for output of disturbed wind data across the low-resolution domain to .Low.DisXY<n_out>.t.vtk (-) [0 to 999]
146 OutDisWindZ - Z coordinates of XY planes for output of disturbed wind data across the low-resolution domain (m) [1 to NOutDisWindXY] [unused for NOutDisWindXY=0]
4 NOutDisWindYZ - Number of YZ planes for output of disturbed wind data across the low-resolution domain to /Low.DisYZ<n_out>.t.vtk (-) [0 to 999]
520,1120,1840,2320 OutDisWindX - X coordinates of YZ planes for output of disturbed wind data across the low-resolution domain (m) [1 to NOutDisWindYZ] [unused for NOutDisWindYZ=0]
1 NOutDisWindXZ - Number of XZ planes for output of disturbed wind data across the low-resolution domain to /Low.DisXZ<n_out>.t.vtk (-) [0 to 999]
0.0 OutDisWindY - Y coordinates of XZ planes for output of disturbed wind data across the low-resolution domain (m) [1 to NOutDisWindXZ] [unused for NOutDisWindXZ=0]
0.2 WrDisDT - Time step for disturbed wind visualization output (s) [>0.0] or DEFAULT [DEFAULT=DT_Low or DT_Low-VTK] [unused for WrDisWind=False and NOutDisWindXY=NOutDisWindYZ=NOutDisWindXZ=0]
--- OUTPUT ---
True SumPrint - Print summary data to .sum? (flag)
99999.9 ChkptTime - Amount of time between creating checkpoint files for potential restart (s) [>0.0]
360 TStart - Time to begin tabular output (s) [>=0.0]
1 OutFileFmt - Format for tabular (time-marching) output file (switch) {1: text file [.out], 2: binary file [.outb], 3: both}
True TabDelim - Use tab delimiters in text tabular output file? (flag) {uses spaces if False}
"ES10.3E2" OutFmt - Format used for text tabular output, excluding the time channel. Resulting field should be 10 characters. (quoted string)
DEFAULT OutAllPlanes - Output all wake planes at all time steps. [DEFAULT=False]
7 NOutRadii - Number of radial nodes for wake output for an individual rotor (-) [0 to 20]
0, 2, 5, 11, 17, 21, 39 OutRadii - List of radial nodes for wake output for an individual rotor (-) [1 to NOutRadii] [unused for NOutRadii=0]
1 NOutDist - Number of downstream distances for wake output for an individual rotor (-) [0 to 9 ]
63.0 OutDist - List of downstream distances for wake output for an individual rotor (m) [1 to NOutDist ] [unused for NOutDist =0]
0 NWindVel - Number of points for wind output (-) [0 to 9]
0.0 WindVelX - List of coordinates in the X direction for wind output (m) [1 to NWindVel] [unused for NWindVel=0]
0.0 WindVelY - List of coordinates in the Y direction for wind output (m) [1 to NWindVel] [unused for NWindVel=0]
90.0 WindVelZ - List of coordinates in the Z direction for wind output (m) [1 to NWindVel] [unused for NWindVel=0]
OutList - The next line(s) contains a list of output parameters. See OutListParameters.xlsx for a listing of available output channels (quoted string)
In addition, I would like to share some of my results in order to seek feedback. These include the instantaneous wake fields on the XY plane (Z = 150 m), the XZ plane (Y = 0 m), and the YZ plane (X = 0.5D).
