FAST.Farm

Dear Dr. Jonkman,

I tried to finish the simulation regarding semisubmersible. However, I encountered a high thrust coefficient under a reference wind speed of 4.0 m and numerical stability with a reference wind velocity of 12.0m. Compared to the original example codes under the steady wind, I made a few changes in ElastoDyn.dat:
WaveDT 0.2→0.25; WaveHs 1.2646→3.75; WaveTp 10→7.50;
WvLowCoff 0.314159→0; WvHighCoff 1.570796→0;
PtfmSurge: 5→0; PtfmPitch: 1.9→0;

The error in the case of 4.0 ms

T1:FARM_InitialCO:FWrap_t0:FAST_Solution0:CalcOutputs_And_SolveForInputs:SolveOption2:SrvD_CalcOut
put:DLL_controller_call:Running with torque and pitch control of the NREL offshore 5MW baseline
wind turbine from DISCON.dll as written by J. Jonkman of NREL/NWTC for use in the IEA Annex XXIII
OC3 studies.  Includes modifications for the Hywind spar.
T2:FARM_InitialCO:FWrap_t0:FAST_Solution0:CalcOutputs_And_SolveForInputs:SolveOption2:SrvD_CalcOut
put:DLL_controller_call:Running with torque and pitch control of the NREL offshore 5MW baseline
wind turbine from DISCON.dll as written by J. Jonkman of NREL/NWTC for use in the IEA Annex XXIII
OC3 studies.  Includes modifications for the Hywind spar.
 Time: 27 of 4000 seconds.  Estimated final completion at 13:30:35.
Warning: SkewedWakeCorrection encountered a large value of chi (90.501 deg), so the yaw
correction will be limited. This warning will not be repeated though the condition may persist.
See the AD15 chi output channels, and consider turning off the Pitt/Peters skew model (set
SkewMod=1) if this condition persists.

Warning: SkewedWakeCorrection encountered a large value of chi (90.014 deg), so the yaw
correction will be limited. This warning will not be repeated though the condition may persist.
See the AD15 chi output channels, and consider turning off the Pitt/Peters skew model (set
SkewMod=1) if this condition persists.
 Time: 28 of 4000 seconds.  Estimated final completion at 13:58:00.
The BEM solution is being turned off due to low TSR.  (TSR = -2620.2). This warning will not be
 Time: 29 of 4000 seconds.  Estimated final completion at 13:34:44.

T1:FARM_UpdateStates:NearWakeCorrection:Wake model is not valid in the propeller-brake region,
i.e., Ct > 2.0.

The selected outputs of 4ms


The error in the case of 12.0 ms

Warning: SkewedWakeCorrection encountered a large value of chi (90.352 deg), so the yaw
correction will be limited. This warning will not be repeated though the condition may persist.
See the AD15 chi output channels, and consider turning off the Pitt/Peters skew model (set
SkewMod=1) if this condition persists.


T1:FARM_UpdateStates:FWrap_Increment:FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:ED_
HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
ED_HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4
radians.
FWrap_Increment:FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:ED_HD_InputOutputSolve:H
ydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
ED_HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4
radians.
FWrap_Increment:FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:ED_HD_InputOutputSolve:H
ydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
ED_HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4
radians.
FWrap_Increment:FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:ED_HD_InputOutputSolve:H
ydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
ED_HD_I
 Time: 18 of 4000 seconds.  Estimated final completion at 01:18:44.

T1:FARM_UpdateStates:FWrap_Increment:FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:ED_
HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
ED_HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4
radians.
FWrap_Increment:FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:ED_HD_InputOutputSolve:H
ydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
ED_HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4
radians.
FWrap_Increment:FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:ED_HD_InputOutputSolve:H
ydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
ED_HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4
radians.
FWrap_Increment:FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:ED_HD_InputOutputSolve:H
ydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
ED_HD_I

The results of 12ms


If possible, pls give me some tips when available. Many thanks

Best regards