Question about wind-wave simulation with TMD

Hello everyone,
I am currently working on designing a fore-aft TMD device for DeepCwind OC4. Preliminary work such as establish a limited degree of freedom model,parameter optimization ect. have already completed. But in the wind-wave joint case, after enable all the degree of freedom and use Turbsim to generate fluctuating wind, FAST encounter errors unceasingly.However,when run the test without TMD or disable the CompInflow ,FAST awlways teminate normally. The content of error,Turbsim and TMD parameters as shown below, I am very confused,and hope that someone can point out my mistakes,thanks in advance.

[code]WARNING: High VNB velocity encountered during induction factor calculation.
Blade number 3, Element number 16
VNW = 10.186, VNB = 106.54
WARNING: High VNB velocity encountered during induction factor calculation.
Blade number 3, Element number 17
VNW = 9.866, VNB = 171.71

FAST_Solution:FAST_AdvanceStates:ED_ABM4:SetCoordSy:Small angle assumption viola
ted in SUBROUTINE
SmllRotTrans() due to a large blade deflection (ElastoDyn SetCoordSy). The solut
ion may be
inaccurate. Simulation continuing, but future warnings from SmllRotTrans() will
be suppressed.
Additional debugging message from SUBROUTINE SmllRotTrans(): 2.9625 s

WARNING: High VNB velocity encountered during induction factor calculation.
Blade number 2, Element number 4
VNW = 10.856, VNB = 104.65
WARNING: High VNB velocity encountered during induction factor calculation.
Blade number 2, Element number 5
VNW = 10.698, VNB = 119.07
WARNING: High VNB velocity encountered during induction factor calculation.
Blade number 2, Element number 6
VNW = 10.12, VNB = 118.05
WARNING: Induced velocity warning written 5 times. The message will not be
repeated, though
the condition may persist.

FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:AD14_CalcOutput:ELEMFR
C:BeddoesModel:ATT
ACH: Blade #2 element #17 is supersonic! Other elements are likely supersonic a
s well.
Supersonic mach nos. will be set to 0.7 to attempt continuation.
AD14_CalcOutput:ELEMFRC:BeddoesModel:ATTACH: Supersonic condition has subsided w
ith Blade #3
element #4.

FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:AD14_CalcOutput:ELEMFR
C:BeddoesModel:ATT
ACH: Blade #2 element #13 is supersonic! Other elements are likely supersonic a
s well.
Supersonic mach nos. will be set to 0.7 to attempt continuation.
AD14_CalcOutput:ELEMFRC:BeddoesModel:ATTACH: Supersonic condition has subsided w
ith Blade #3
element #4.
AD14_CalcOutput:ELEMFRC:BeddoesModel:ATTACH: Blade #3 element #15 is supersonic!
Other elements
are likely supersonic as well. Supersonic mach nos. will be set to 0.7 to attemp
t continuation.

FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:InflowWind_CalcOutput:
CalcOutput:IfW_TSF
FWind_CalcOutput [position=(NaN, NaN, NaN) in wind-file coordinates]: Error: FF
wind array was
exhausted at 3 seconds (trying to access data at NaN seconds). [/code]

[code]--------Turbine/Model Specifications-----------------------
17 NumGrid_Z - Vertical grid-point matrix dimension
17 NumGrid_Y - Horizontal grid-point matrix dimension
0.05 TimeStep - Time step [seconds]
710 AnalysisTime - Length of analysis time series [seconds] (program will add time if necessary: AnalysisTime = MAX(AnalysisTime, UsableTime+GridWidth/MeanHHWS) )
700 UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds)
90.00 HubHt - Hub height [m] (should be > 0.5GridHeight)
150.00 GridHeight - Grid height [m]
150.00 GridWidth - Grid width [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”=Kaimal, “IECVKM”=von Karman, “GP_LLJ”, “NWTCUP”, “SMOOTH”, “WF_UPW”, “WF_07D”, “WF_14D”, “TIDAL”, or “NONE”)
“1-ED3” IECstandard - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. “1-Ed2”) )
“11” 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 - Wind profile type (“JET”;“LOG”=logarithmic;“PL”=power law;“H2L”=Log law for TIDAL spectral model;“IEC”=PL on rotor disk, LOG elsewhere; or “default”)
90 RefHt - Height of the reference wind speed [m]
37 URef - Mean (total) wind speed at the reference height [m/s] (or “default” for JET wind profile)
default ZJetMax - Jet height [m] (used only for JET wind profile, valid 70-490 m)
0.11 PLExp - Power law exponent [-] (or “default”)
default Z0 - Surface roughness length [m] (or “default”) [/code]

---------------------- TMD DEGREES OF FREEDOM --------------------------------- TRUE TMD_X_DOF - DOF on or off (flag) False TMD_Y_DOF - DOF on or off (flag) ---------------------- TMD INITIAL CONDITIONS --------------------------------- 0 TMD_X_DSP - TMD_X initial displacement (m) 0 TMD_Y_DSP - TMD_Y initial displacement (m) ---------------------- TMD CONFIGURATION -------------------------------------- 0 TMD_P_X - at rest position of TMDs (X) (m) 0 TMD_P_Y - at rest position of TMDs (Y) (m) 0 TMD_P_Z - at rest position of TMDs (Z) (m) 8 TMD_X_DWSP - DW stop position (maximum X mass displacement) (m) -8 TMD_X_UWSP - UW stop position (minimum X mass displacement) (m) 0 TMD_Y_PLSP - positive lateral stop position (maximum Y mass displacement) (m) 0 TMD_Y_NLSP - negative lateral stop position (minimum Y mass displacement) (m) ---------------------- TMD MASS, STIFFNESS, & DAMPING ------------------------- 40000 TMD_X_M - TMD mass (kg) 0 TMD_Y_M - TMD mass (kg) 1000 TMD_X_K - TMD stiffness (N/m) 0 TMD_Y_K - TMD stiffness (N/m) 1000 TMD_X_C - TMD damping (N/(m/s)) 0 TMD_Y_C - TMD damping (N/(m/s)) 500000 TMD_X_KS - stop spring stiffness (N/m) 0 TMD_Y_KS - stop spring stiffness (N/m) 500000 TMD_X_CS - stop spring damping (N/(m/s)) 0 TMD_Y_CS - stop spring damping (N/(m/s))

Best regards,
Tongyi.Zhuang

Dear Tongyi,

It looks like the model went numerically unstable for some reason. I first see that the blade undergoes large deflection, which then triggers a number of warnings until a fatal error is reached. Perhaps the addition of the TMD requires the use of a smaller time step to keep the model numerically stable?

Best regards,