## Modelling

Discuss theory and modeling of wind-turbine structures.

Moderator: Bonnie.Jonkman

Patrick.Lai
Posts: 7
Joined: Mon Sep 07, 2020 6:52 am
Organization: Hongkong University of science and technology
Location: Hongkong

### Modelling

Dear all,

I am using FASTV7 to model the NREL 5WM wind turbine (including monopile). To consider the soil-pile interaction, I used the intact UserTwrLd_DS.f90 provided by Dr. Jonkman for OC3 tasks. I compiled the code and the calculation goes well.

For analyzing the fatigue response of the monopile, I have to output the pile shear force and bending moment ( at FA direction) at each depth. I use "TwHt(1,2,3...)FLxt" and "TwHt(1,2,3...)MLyt" to get the results I need. However, the extracted distributions of shear force and moment of the monopile look very strange:

1) The pile moment increases with depth (from the mudline), which seems unacceptable to me because the soil springs provide resistance to the monopile to resist the wind and wave load. Therefore, the pile moment should gradually decrease to 0 due to the soil resistance contribution after a certain depth, as shown in the attachment.

2) The shear force at the pile section near the pile bottom still has a large value, which is also puzzled me. For the equilibrium of the monopile, all the lateral loads induced by wind and wave should be equal to the total lateral soil resistance provided by the distributed springs. Therefore, the shear force near the pile bottom should be approximately 0.

I carefully check the CalcOuts in fast.f90 to get insight into the shear force and moment outputs. But I don't see any problem.

I would like to hear any suggestions on how to get the right pile shear force and moment. Thanks in advance.

Patrick
Attachments
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Jason.Jonkman
Posts: 5763
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

### Re: Modelling

Dear Patrick,

I agree that the shear force and bending moment in the pile should tend toward zero near the bottom of the pile. If you are not seeing that in the results, I would expect a problem with your model set-up, but it is difficult for me to guess what that is. Do you have PtfmModel = 2 in the FAST v7 primary input? And do you have platform DOFs enabled in the FAST v7 platform input file (perhaps with heave and yaw disabled), as well as TwrDraft = PtfmCM = PtfmRef = 56 m, PtfmLdMod = 0, and TwrLdMod = 2?

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Patrick.Lai
Posts: 7
Joined: Mon Sep 07, 2020 6:52 am
Organization: Hongkong University of science and technology
Location: Hongkong

### Re: Modelling

Dear Jason,

Indeed, I have PtfmModel = 2 in the FAST v7 primary input as well as TwrDraft = PtfmCM = PtfmRef = 56 m, PtfmLdMod = 0, and TwrLdMod = 2. But all the platform DOFs were set as "False". I have enabled them as you told me and now the results are reasonable. I really appreciate for your kind help.

To avoid any other mistakes, I'd like to post my primary and platform input files here(as follows). I was wondering if you could have a quick check for me. Thanks in advance.

Best regards,
Patrick

------- FAST INPUT FILE --------------------------------------------------------
NREL 5.0 MW Baseline Wind Turbine for Use in Offshore Analysis.
Properties from Dutch Offshore Wind Energy Converter (DOWEC) 6MW Pre-Design (10046_009.pdf) and REpower 5M 5MW (5m_uk.pdf); Compatible with FAST v7.0.
---------------------- SIMULATION CONTROL --------------------------------------
False Echo - Echo input data to "echo.out" (flag)
1 ADAMSPrep - ADAMS preprocessor mode {1: Run FAST, 2: use FAST as a preprocessor to create an ADAMS model, 3: do both} (switch)
1 AnalMode - Analysis mode {1: Run a time-marching simulation, 2: create a periodic linearized model} (switch)
3 NumBl - Number of blades (-)
630.0 TMax - Total run time (s)
0.001 DT - Integration time step (s)
---------------------- TURBINE CONTROL -----------------------------------------
0 YCMode - Yaw control mode {0: none, 1: user-defined from routine UserYawCont, 2: user-defined from Simulink} (switch)
9999.9 TYCOn - Time to enable active yaw control (s) [unused when YCMode=0]
1 PCMode - Pitch control mode {0: none, 1: user-defined from routine PitchCntrl, 2: user-defined from Simulink} (switch)
0.0 TPCOn - Time to enable active pitch control (s) [unused when PCMode=0]
2 VSContrl - Variable-speed control mode {0: none, 1: simple VS, 2: user-defined from routine UserVSCont, 3: user-defined from Simulink} (switch)
9999.9 VS_RtGnSp - Rated generator speed for simple variable-speed generator control (HSS side) (rpm) [used only when VSContrl=1]
9999.9 VS_RtTq - Rated generator torque/constant generator torque in Region 3 for simple variable-speed generator control (HSS side) (N-m) [used only when VSContrl=1]
9999.9 VS_Rgn2K - Generator torque constant in Region 2 for simple variable-speed generator control (HSS side) (N-m/rpm^2) [used only when VSContrl=1]
9999.9 VS_SlPc - Rated generator slip percentage in Region 2 1/2 for simple variable-speed generator control (%) [used only when VSContrl=1]
2 GenModel - Generator model {1: simple, 2: Thevenin, 3: user-defined from routine UserGen} (switch) [used only when VSContrl=0]
True GenTiStr - Method to start the generator {T: timed using TimGenOn, F: generator speed using SpdGenOn} (flag)
True GenTiStp - Method to stop the generator {T: timed using TimGenOf, F: when generator power = 0} (flag)
9999.9 SpdGenOn - Generator speed to turn on the generator for a startup (HSS speed) (rpm) [used only when GenTiStr=False]
0.0 TimGenOn - Time to turn on the generator for a startup (s) [used only when GenTiStr=True]
9999.9 TimGenOf - Time to turn off the generator (s) [used only when GenTiStp=True]
1 HSSBrMode - HSS brake model {1: simple, 2: user-defined from routine UserHSSBr} (switch)
9999.9 THSSBrDp - Time to initiate deployment of the HSS brake (s)
9999.9 TiDynBrk - Time to initiate deployment of the dynamic generator brake [CURRENTLY IGNORED] (s)
9999.9 TTpBrDp(1) - Time to initiate deployment of tip brake 1 (s)
9999.9 TTpBrDp(2) - Time to initiate deployment of tip brake 2 (s)
9999.9 TTpBrDp(3) - Time to initiate deployment of tip brake 3 (s) [unused for 2 blades]
9999.9 TBDepISp(1) - Deployment-initiation speed for the tip brake on blade 1 (rpm)
9999.9 TBDepISp(2) - Deployment-initiation speed for the tip brake on blade 2 (rpm)
9999.9 TBDepISp(3) - Deployment-initiation speed for the tip brake on blade 3 (rpm) [unused for 2 blades]
9999.9 TYawManS - Time to start override yaw maneuver and end standard yaw control (s)
9999.9 TYawManE - Time at which override yaw maneuver reaches final yaw angle (s)
0.0 NacYawF - Final yaw angle for override yaw maneuvers (degrees)
9999.9 TPitManS(1) - Time to start override pitch maneuver for blade 1 and end standard pitch control (s)
9999.9 TPitManS(2) - Time to start override pitch maneuver for blade 2 and end standard pitch control (s)
9999.9 TPitManS(3) - Time to start override pitch maneuver for blade 3 and end standard pitch control (s) [unused for 2 blades]
9999.9 TPitManE(1) - Time at which override pitch maneuver for blade 1 reaches final pitch (s)
9999.9 TPitManE(2) - Time at which override pitch maneuver for blade 2 reaches final pitch (s)
9999.9 TPitManE(3) - Time at which override pitch maneuver for blade 3 reaches final pitch (s) [unused for 2 blades]
0.0 BlPitch(1) - Blade 1 initial pitch (degrees)
0.0 BlPitch(2) - Blade 2 initial pitch (degrees)
0.0 BlPitch(3) - Blade 3 initial pitch (degrees) [unused for 2 blades]
0.0 BlPitchF(1) - Blade 1 final pitch for pitch maneuvers (degrees)
0.0 BlPitchF(2) - Blade 2 final pitch for pitch maneuvers (degrees)
0.0 BlPitchF(3) - Blade 3 final pitch for pitch maneuvers (degrees) [unused for 2 blades]
---------------------- ENVIRONMENTAL CONDITIONS --------------------------------
9.80665 Gravity - Gravitational acceleration (m/s^2)
---------------------- FEATURE FLAGS -------------------------------------------
True FlapDOF1 - First flapwise blade mode DOF (flag)
True FlapDOF2 - Second flapwise blade mode DOF (flag)
True EdgeDOF - First edgewise blade mode DOF (flag)
False TeetDOF - Rotor-teeter DOF (flag) [unused for 3 blades]
True DrTrDOF - Drivetrain rotational-flexibility DOF (flag)
True GenDOF - Generator DOF (flag)
True YawDOF - Yaw DOF (flag)
True TwFADOF1 - First fore-aft tower bending-mode DOF (flag)
True TwFADOF2 - Second fore-aft tower bending-mode DOF (flag)
True TwSSDOF1 - First side-to-side tower bending-mode DOF (flag)
True TwSSDOF2 - Second side-to-side tower bending-mode DOF (flag)
True CompAero - Compute aerodynamic forces (flag)
False CompNoise - Compute aerodynamic noise (flag)
---------------------- INITIAL CONDITIONS --------------------------------------
0.0 OoPDefl - Initial out-of-plane blade-tip displacement (meters)
0.0 IPDefl - Initial in-plane blade-tip deflection (meters)
0.0 TeetDefl - Initial or fixed teeter angle (degrees) [unused for 3 blades]
0.0 Azimuth - Initial azimuth angle for blade 1 (degrees)
12.1 RotSpeed - Initial or fixed rotor speed (rpm)
0.0 NacYaw - Initial or fixed nacelle-yaw angle (degrees)
0.0 TTDspFA - Initial fore-aft tower-top displacement (meters)
0.0 TTDspSS - Initial side-to-side tower-top displacement (meters)
---------------------- TURBINE CONFIGURATION -----------------------------------
63.0 TipRad - The distance from the rotor apex to the blade tip (meters)
1.5 HubRad - The distance from the rotor apex to the blade root (meters)
1 PSpnElN - Number of the innermost blade element which is still part of the pitchable portion of the blade for partial-span pitch control [1 to BldNodes] [CURRENTLY IGNORED] (-)
0.0 UndSling - Undersling length [distance from teeter pin to the rotor apex] (meters) [unused for 3 blades]
0.0 HubCM - Distance from rotor apex to hub mass [positive downwind] (meters)
-5.01910 OverHang - Distance from yaw axis to rotor apex [3 blades] or teeter pin [2 blades] (meters)
1.9 NacCMxn - Downwind distance from the tower-top to the nacelle CM (meters)
0.0 NacCMyn - Lateral distance from the tower-top to the nacelle CM (meters)
1.75 NacCMzn - Vertical distance from the tower-top to the nacelle CM (meters)
87.6 TowerHt - Height of tower above ground level [onshore] or MSL [offshore] (meters)
1.96256 Twr2Shft - Vertical distance from the tower-top to the rotor shaft (meters)
0.0 TwrRBHt - Tower rigid base height (meters)
-5.0 ShftTilt - Rotor shaft tilt angle (degrees)
0.0 Delta3 - Delta-3 angle for teetering rotors (degrees) [unused for 3 blades]
-2.5 PreCone(1) - Blade 1 cone angle (degrees)
-2.5 PreCone(2) - Blade 2 cone angle (degrees)
-2.5 PreCone(3) - Blade 3 cone angle (degrees) [unused for 2 blades]
0.0 AzimB1Up - Azimuth value to use for I/O when blade 1 points up (degrees)
---------------------- MASS AND INERTIA ----------------------------------------
0.0 YawBrMass - Yaw bearing mass (kg)
240.00E3 NacMass - Nacelle mass (kg)
56.78E3 HubMass - Hub mass (kg)
0.0 TipMass(1) - Tip-brake mass, blade 1 (kg)
0.0 TipMass(2) - Tip-brake mass, blade 2 (kg)
0.0 TipMass(3) - Tip-brake mass, blade 3 (kg) [unused for 2 blades]
2607.89E3 NacYIner - Nacelle inertia about yaw axis (kg m^2)
534.116 GenIner - Generator inertia about HSS (kg m^2)
115.926E3 HubIner - Hub inertia about rotor axis [3 blades] or teeter axis [2 blades] (kg m^2)
---------------------- DRIVETRAIN ----------------------------------------------
100.0 GBoxEff - Gearbox efficiency (%)
94.4 GenEff - Generator efficiency [ignored by the Thevenin and user-defined generator models] (%)
97.0 GBRatio - Gearbox ratio (-)
False GBRevers - Gearbox reversal {T: if rotor and generator rotate in opposite directions} (flag)
28.1162E3 HSSBrTqF - Fully deployed HSS-brake torque (N-m)
0.6 HSSBrDT - Time for HSS-brake to reach full deployment once initiated (sec) [used only when HSSBrMode=1]
"Dummy" DynBrkFi - File containing a mech-gen-torque vs HSS-speed curve for a dynamic brake [CURRENTLY IGNORED] (quoted string)
867.637E6 DTTorSpr - Drivetrain torsional spring (N-m/rad)
6.215E6 DTTorDmp - Drivetrain torsional damper (N-m/(rad/s))
---------------------- SIMPLE INDUCTION GENERATOR ------------------------------
9999.9 SIG_SlPc - Rated generator slip percentage (%) [used only when VSContrl=0 and GenModel=1]
9999.9 SIG_SySp - Synchronous (zero-torque) generator speed (rpm) [used only when VSContrl=0 and GenModel=1]
9999.9 SIG_RtTq - Rated torque (N-m) [used only when VSContrl=0 and GenModel=1]
9999.9 SIG_PORt - Pull-out ratio (Tpullout/Trated) (-) [used only when VSContrl=0 and GenModel=1]
---------------------- THEVENIN-EQUIVALENT INDUCTION GENERATOR -----------------
9999.9 TEC_Freq - Line frequency [50 or 60] (Hz) [used only when VSContrl=0 and GenModel=2]
9998 TEC_NPol - Number of poles [even integer > 0] (-) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_SRes - Stator resistance (ohms) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_RRes - Rotor resistance (ohms) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_VLL - Line-to-line RMS voltage (volts) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_SLR - Stator leakage reactance (ohms) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_RLR - Rotor leakage reactance (ohms) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_MR - Magnetizing reactance (ohms) [used only when VSContrl=0 and GenModel=2]
---------------------- PLATFORM ------------------------------------------------
2 PtfmModel - Platform model {0: none, 1: onshore, 2: fixed bottom offshore, 3: floating offshore} (switch)
"NRELOffshrBsline5MW_Platform_Monopile_RF_DS.dat" PtfmFile - Name of file containing platform properties (quoted string) [unused when PtfmModel=0]
---------------------- TOWER ---------------------------------------------------
144 TwrNodes - Number of tower nodes used for analysis (-)
"NRELOffshrBsline5MW_Tower_Monopile_RF_DS.dat" TwrFile - Name of file containing tower properties (quoted string)
---------------------- NACELLE-YAW ---------------------------------------------
9028.32E6 YawSpr - Nacelle-yaw spring constant (N-m/rad)
19.16E6 YawDamp - Nacelle-yaw damping constant (N-m/(rad/s))
0.0 YawNeut - Neutral yaw position--yaw spring force is zero at this yaw (degrees)
---------------------- FURLING -------------------------------------------------
False Furling - Read in additional model properties for furling turbine (flag)
"Dummy" FurlFile - Name of file containing furling properties (quoted string) [unused when Furling=False]
---------------------- ROTOR-TEETER --------------------------------------------
0 TeetMod - Rotor-teeter spring/damper model {0: none, 1: standard, 2: user-defined from routine UserTeet} (switch) [unused for 3 blades]
0.0 TeetDmpP - Rotor-teeter damper position (degrees) [used only for 2 blades and when TeetMod=1]
0.0 TeetDmp - Rotor-teeter damping constant (N-m/(rad/s)) [used only for 2 blades and when TeetMod=1]
0.0 TeetCDmp - Rotor-teeter rate-independent Coulomb-damping moment (N-m) [used only for 2 blades and when TeetMod=1]
0.0 TeetSStP - Rotor-teeter soft-stop position (degrees) [used only for 2 blades and when TeetMod=1]
0.0 TeetHStP - Rotor-teeter hard-stop position (degrees) [used only for 2 blades and when TeetMod=1]
0.0 TeetSSSp - Rotor-teeter soft-stop linear-spring constant (N-m/rad) [used only for 2 blades and when TeetMod=1]
0.0 TeetHSSp - Rotor-teeter hard-stop linear-spring constant (N-m/rad) [used only for 2 blades and when TeetMod=1]
---------------------- TIP-BRAKE -----------------------------------------------
0.0 TBDrConN - Tip-brake drag constant during normal operation, Cd*Area (m^2)
0.0 TBDrConD - Tip-brake drag constant during fully-deployed operation, Cd*Area (m^2)
0.0 TpBrDT - Time for tip-brake to reach full deployment once released (sec)
"NRELOffshrBsline5MW_Blade.dat" BldFile(1) - Name of file containing properties for blade 1 (quoted string)
"NRELOffshrBsline5MW_Blade.dat" BldFile(2) - Name of file containing properties for blade 2 (quoted string)
"NRELOffshrBsline5MW_Blade.dat" BldFile(3) - Name of file containing properties for blade 3 (quoted string) [unused for 2 blades]
---------------------- AERODYN -------------------------------------------------
"NRELOffshrBsline5MW_AeroDyn.ipt" ADFile - Name of file containing AeroDyn input parameters (quoted string)
---------------------- NOISE ---------------------------------------------------
"Dummy" NoiseFile - Name of file containing aerodynamic noise input parameters (quoted string) [used only when CompNoise=True]
---------------------- LINEARIZATION CONTROL -----------------------------------
"NRELOffshrBsline5MW_Linear.dat" LinFile - Name of file containing FAST linearization parameters (quoted string) [unused when AnalMode=1]
---------------------- OUTPUT --------------------------------------------------
True SumPrint - Print summary data to "<RootName>.fsm" (flag)
1 OutFileFmt - Format for tabular (time-marching) output files (1: text file[<RootName>.out], 2: Binary file [<RootName>.outb], 3: both) (switch)
True TabDelim - Generate a tab-delimited tabular output file. (flag)
"ES10.3E2" OutFmt - Format used for tabular output except time. Resulting field should be 10 characters. (quoted string) [not checked for validity!]
30.0 TStart - Time to begin tabular output (s)
10 DecFact - Decimation factor for tabular output {1: output every time step} (-)
1.0 SttsTime - Amount of time between screen status messages (sec)
-3.09528 NcIMUxn - Downwind distance from the tower-top to the nacelle IMU (meters)
0.0 NcIMUyn - Lateral distance from the tower-top to the nacelle IMU (meters)
2.23336 NcIMUzn - Vertical distance from the tower-top to the nacelle IMU (meters)
1.912 ShftGagL - Distance from rotor apex [3 blades] or teeter pin [2 blades] to shaft strain gages [positive for upwind rotors] (meters)
9 NTwGages - Number of tower nodes that have strain gages for output [0 to 9] (-)
1,9,13,17,21,25,29,33,37 TwrGagNd - List of tower nodes that have strain gages [1 to TwrNodes] (-) [unused if NTwGages=0]
0 NBlGages - Number of blade nodes that have strain gages for output [0 to 9] (-)
5,9,13 BldGagNd - List of blade nodes that have strain gages [1 to BldNodes] (-) [unused if NBlGages=0]
OutList - The next line(s) contains a list of output parameters. See OutList.txt for a listing of available output channels, (-)
"WindVxi , WindVyi , WindVzi" - Longitudinal, lateral, and vertical wind speeds
"WaveElev" - Wave elevation at the platform reference point
"RotSpeed , GenSpeed" - Low-speed shaft and high-speed shaft speeds
"TTDspFA , TTDspSS" - Tower top fore-aft and side-to-side displacements
"PtfmTDxi , PtfmTDyi , PtfmRDxi , PtfmRDyi" - Fore-aft, side-to-side, roll, and pitch displacements of the monopile at the mudline
"YawBrFxp , YawBrFyp" - Fore-aft shear, side-to-side shear, and vertical forces at the top of the tower (not rotating with nacelle yaw)
"YawBrMxp , YawBrMyp" - Side-to-side bending, fore-aft bending, and yaw moments at the top of the tower (not rotating with nacelle yaw)
"TwHt1TDxt, TwHt1FLxt, TwHt1MLyt" - Local side-to-side and fore-aft bending moments at tower gage
"TwHt2TDxt, TwHt2FLxt, TwHt2MLyt"
"TwHt3TDxt, TwHt3FLxt, TwHt3MLyt"
"TwHt4TDxt, TwHt4FLxt, TwHt4MLyt"
"TwHt5TDxt, TwHt5FLxt, TwHt5MLyt"
"TwHt6TDxt, TwHt6FLxt, TwHt6MLyt"
"TwHt7TDxt, TwHt7FLxt, TwHt7MLyt"
"TwHt8TDxt, TwHt8FLxt, TwHt8MLyt"
"TwHt9TDxt, TwHt9FLxt, TwHt9MLyt"
"TwrBsFxt , TwrBsFyt , TwrBsFzt" - Fore-aft shear, side-to-side shear, and vertical forces at the mudline
"TwrBsMxt , TwrBsMyt , TwrBsMzt" - Side-to-side bending, fore-aft bending, and yaw moments at the mudline
"PtfmSurge, PtfmSway , PtfmRoll , PtfmPitch" - Platform surge, sway, roll, and pitch displacements (for use in calculating in Crunch the tower-top displacements in the inertia frame)
END of FAST input file (the word "END" must appear in the first 3 columns of this last line).
--------------------------------------------------------------------------------

---------------------- FAST PLATFORM FILE --------------------------------------
NREL 5.0 MW offshore baseline monopile platform with flexible foundation input properties.
---------------------- FEATURE FLAGS (CONT) ------------------------------------
True PtfmSgDOF - Platform horizontal surge translation DOF (flag)
True PtfmSwDOF - Platform horizontal sway translation DOF (flag)
False PtfmHvDOF - Platform vertical heave translation DOF (flag)
True PtfmRDOF - Platform roll tilt rotation DOF (flag)
True PtfmPDOF - Platform pitch tilt rotation DOF (flag)
False PtfmYDOF - Platform yaw rotation DOF (flag)
---------------------- INITIAL CONDITIONS (CONT) -------------------------------
0.0 PtfmSurge - Initial or fixed horizontal surge translational displacement of platform (meters)
0.0 PtfmSway - Initial or fixed horizontal sway translational displacement of platform (meters)
0.0 PtfmHeave - Initial or fixed vertical heave translational displacement of platform (meters)
0.0 PtfmRoll - Initial or fixed roll tilt rotational displacement of platform (degrees)
0.0 PtfmPitch - Initial or fixed pitch tilt rotational displacement of platform (degrees)
0.0 PtfmYaw - Initial or fixed yaw rotational displacement of platform (degrees)
---------------------- TURBINE CONFIGURATION (CONT) ----------------------------
56.0 TwrDraft - Downward distance from the ground level [onshore] or MSL [offshore] to the tower base platform connection (meters)
56.0 PtfmCM - Downward distance from the ground level [onshore] or MSL [offshore] to the platform CM (meters)
56.0 PtfmRef - Downward distance from the ground level [onshore] or MSL [offshore] to the platform reference point (meters)
---------------------- MASS AND INERTIA (CONT) ---------------------------------
0.0 PtfmMass - Platform mass (kg)
0.0 PtfmRIner - Platform inertia for roll tilt rotation about the platform CM (kg m^2)
0.0 PtfmPIner - Platform inertia for pitch tilt rotation about the platform CM (kg m^2)
0.0 PtfmYIner - Platfrom inertia for yaw rotation about the platform CM (kg m^2)
---------------------- PLATFORM (CONT) -----------------------------------------
0 PtfmLdMod - Platform loading model {0: none, 1: user-defined from routine UserPtfmLd} (switch)
---------------------- TOWER (CONT) --------------------------------------------
2 TwrLdMod - Tower loading model {0: none, 1: Morison's equation, 2: user-defined from routine UserTwrLd} (switch)
6.0 TwrDiam - Tower diameter in Morison's equation (meters) [used only when TwrLdMod=1]
1.6 TwrCA - Normalized hydrodynamic added mass coefficient in Morison's equation (-) [used only when TwrLdMod=1] [determines TwrCM=1+TwrCA]
0.65 TwrCD - Normalized hydrodynamic viscous drag coefficient in Morison's equation (-) [used only when TwrLdMod=1]
---------------------- WAVES ---------------------------------------------------
1025.0 WtrDens - Water density (kg/m^3)
20.0 WtrDpth - Water depth (meters)
2 WaveMod - Incident wave kinematics model {0: none=still water, 1: plane progressive (regular), 2: JONSWAP/Pierson-Moskowitz spectrum (irregular), 3: user-defind spectrum from routine UserWaveSpctrm (irregular), 4: GH Bladed wave data} (switch)
3 WaveStMod - Model for stretching incident wave kinematics to instantaneous free surface {0: none=no stretching, 1: vertical stretching, 2: extrapolation stretching, 3: Wheeler stretching} (switch) [unused when WaveMod=0]
2000 WaveTMax - Analysis time for incident wave calculations (sec) [unused when WaveMod=0] [determines WaveDOmega=2Pi/WaveTMax in the IFFT]
0.05 WaveDT - Time step for incident wave calculations (sec) [unused when WaveMod=0] [0.1<=WaveDT<=1.0 recommended] [determines WaveOmegaMax=Pi/WaveDT in the IFFT]
6.0 WaveHs - Significant wave height of incident waves (meters) [used only when WaveMod=1 or 2]
10.0 WaveTp - Peak spectral period of incident waves (sec) [used only when WaveMod=1 or 2]
DEFAULT WavePkShp - Peak shape parameter of incident wave spectrum (-) or DEFAULT (unquoted string) [used only when WaveMod=2] [use 1.0 for Pierson-Moskowitz]
0 WaveDir - Incident wave propagation heading direction (degrees) [unused when WaveMod=0 or 4]
1234567891 WaveSeed(1) - First random seed of incident waves [-2147483648 to 2147483647] (-) [unused when WaveMod=0 or 4]
1011121314 WaveSeed(2) - Second random seed of incident waves [-2147483648 to 2147483647] (-) [unused when WaveMod=0 or 4]
"Dummy" GHWvFile - Root name of GH Bladed files containing wave data (quoted string) [used only when WaveMod=4]
---------------------- CURRENT -------------------------------------------------
1 CurrMod - Current profile model {0: none=no current, 1: standard, 2: user-defined from routine UserCurrent} (switch)
0.55 CurrSSV0 - Sub-surface current velocity at still water level (m/s) [used only when CurrMod=1]
"DEFAULT" CurrSSDir - Sub-surface current heading direction (degrees) or DEFAULT (unquoted string) [used only when CurrMod=1]
20.0 CurrNSRef - Near-surface current reference depth (meters) [used only when CurrMod=1]
0.0 CurrNSV0 - Near-surface current velocity at still water level (m/s) [used only when CurrMod=1]
0.0 CurrNSDir - Near-surface current heading direction (degrees) [used only when CurrMod=1]
0.0 CurrDIV - Depth-independent current velocity (m/s) [used only when CurrMod=1]
0.0 CurrDIDir - Depth-independent current heading direction (degrees) [used only when CurrMod=1]
---------------------- OUTPUT (CONT) -------------------------------------------
0 NWaveKin - Number of points where the wave kinematics can be output [0 to 9] (-)
2 4 6 8 10 12 14 15 16 WaveKinNd - List of tower nodes that have wave kinematics sensors [1 to TwrNodes] (-) [unused if NWaveKin=0]

Jason.Jonkman
Posts: 5763
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### Re: Modelling

Dear Patrick,

Yes, by enabling the platform DOFs, loads can no longer be transferred to the inertial frame through the bottom of the pile. I don't see any other issues with your FAST v7 input files.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Patrick.Lai
Posts: 7
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Organization: Hongkong University of science and technology
Location: Hongkong

### Re: Modelling

Dear Jason,

Got it. I really appreciate for your help and high-efficiency.

Best regards,
Patrick

Satish.Jawalageri
Posts: 117
Joined: Sun May 31, 2020 4:57 am
Organization: University College Dublin
Location: Ireland

### Re: Modelling

Dear Jason,

1. I want to model TP and MP (See below the joint levels) in which basically TP and MP overlaps but as the subdyn module says overlap of joint is not yet available. So is there any alternative way that we can incorporate this overlap?

JointID JointXss JointYss JointZss [Coordinates of Member joints in SS-Coordinate System]
(-) (m) (m) (m)
1 0.00000 0.00000 -20.00000
2 0.00000 0.00000 -10.00000
3 0.00000 0.00000 0.00000
4 0.00000 0.00000 6.00000
5 0.00000 0.00000 -6.00000
6 0.00000 0.00000 10.00000

MemberID MJointID1 MJointID2 MPropSetID1 MPropSetID2 COSMID
(-) (-) (-) (-) (-) (-)
1 1 2 1 1
2 2 3 1 1
3 3 4 1 1
4 5 6 1 1

2. Could I know when soildyn module will be releasing?

Thanks,
Satish J

Jason.Jonkman
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Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
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### Re: Modelling

Dear Satish,

The member overlap that is not considered in SubDyn, as mentioned in the SubDyn documentation, is referring to multiple members connecting to the same joint from different angles. For example, if two circular members connect to a given joint 90 degrees apart, the overlap at the corners of the structure is not considered directly, This could, e.g., lead to a misprediction of the mass and stiffness.

The overlap you are referring to is quite different--one member fitted over another. The big problem I see being able to model this in SubDyn is that there is no specific model for the grout between the TP and pile and between the TP and tower. Instead of modeling this as overlapping members, I think it would be preferable to model the TP region as nonoverlapping member with unique beam properties, accounting for unique diameter, thickness and material properties of the TP region.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Satish.Jawalageri
Posts: 117
Joined: Sun May 31, 2020 4:57 am
Organization: University College Dublin
Location: Ireland

### Re: Modelling

Dear Jason,

Okay, I that OK to have diameter of TP greater than MP in subdyn?

and what about the second question (when can we expect the release of soildyn module)?

Thanks,
Satish J

Jason.Jonkman
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Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
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### Re: Modelling

Dear Satish,

I'm not sure I understand your question regarding the TP diameter please clarify.

Regarding SoilDyn I know that the OpenFAST development team intends to merge the following pull request into dev before merging in SoilDyn: https://github.com/OpenFAST/openfast/pull/537. I don't believe that there is an exact date, but I would guess this will happen in about a month.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Satish.Jawalageri
Posts: 117
Joined: Sun May 31, 2020 4:57 am
Organization: University College Dublin
Location: Ireland

### Re: Modelling

Dear Jason,

I have diameter of TP (say 8m) which is greater than diameter of MP (say 7.5m), will subdyn take it as tapered section?

Thanks,
Satish J

Jason.Jonkman
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### Re: Modelling

Dear Satish,

SubDyn will only apply a stepwise taper to a member if NDiv > 1 and MPropSetIED1 /= MPropSetID2. Two distinct members connected at a joint do not need the same diameter and SubDyn will not force a tapered transition between the two members.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Satish.Jawalageri
Posts: 117
Joined: Sun May 31, 2020 4:57 am
Organization: University College Dublin
Location: Ireland

### Re: Modelling

Dear Jason,

Will it be like as shown in the figure, if so, how they are connected?

Thanks,
Satish J
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Jason.Jonkman
Posts: 5763
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
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### Re: Modelling

Dear Satish,

Yes, that is correct. One member will be rigidly connected to the other (via a cantilevered connection).

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Satish.Jawalageri
Posts: 117
Joined: Sun May 31, 2020 4:57 am
Organization: University College Dublin
Location: Ireland

Dear Jason,