Hi @Jason.Jonkman:
I changed value of DT to make it smaller but the model is still unstable. I am still getting the following error.
FAST_Solution:FAST_AdvanceStates:ED_ABM4:ED_CalcContStateDeriv:SetCoordSy:Small angle assumption
violated in SUBROUTINE SmllRotTrans() due to a large blade deflection (ElastoDyn SetCoordSy). The
solution may be inaccurate. Simulation continuing, but future warnings from SmllRotTrans() will
be suppressed.
Additional debugging message from SUBROUTINE SmllRotTrans(): 0.725 s
FAST_Solution:FAST_AdvanceStates:SolveOption2c_Inp2AD_SrvD:InflowWind_CalcOutput:CalcOutput:IfW_FF
Wind_CalcOutput [position=(-16.053, -42.159, 314.03) in wind-file coordinates]: FF wind array
boundaries violated. Grid too small in Z direction (Z=314.03 m is above the grid).
OpenFAST encountered an error at simulation time 1.025 of 3600 seconds.
Simulation error level: FATAL ERROR
Also note the following:
- The parked/idle case runs fine. The only change I made was to set GenDOF=True and model runs with no problem
- The original case for 200 m deep water also gives error when I try to run the parked/standstill case
- For lower wind speed that is 9 m/s the model still gives error for the parked/standstill case.
Not sure how to solve this problem as yet.
Problem No. 2 - I also have another problem. It has persisted for some time but only now bringing it to your attention. I have tried to a wind only case for 11 m/s turbulent wind and get the following error:
FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:RotCalcOutput:BEMT_CalcOutput(node 3,
blade 1):UA_CalcOutput:UA_BlendSteady:Temporarily turning off UA due to high angle of attack or
low relative velocity. This warning will not be repeated though the condition may persist.
FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:RotCalcOutput:BEMT_CalcOutput(node 50,
blade 1):UA_CalcOutput:Mach number exceeds 0.3. Theory is invalid. This warning will not be
repeated though the condition may persist.
Warning: SkewedWakeCorrection encountered a large value of chi (90.407 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.
FAST_Solution:FAST_AdvanceStates:SolveOption2c_Inp2AD_SrvD:InflowWind_CalcOutput:CalcOutput:IfW_FF
Wind_CalcOutput [position=(0.13124, -1.42073E-03, 2.421) in wind-file coordinates]: FF wind
array boundaries violated. Grid too small in Z direction (height (Z=2.421 m) is below the grid
and no tower points are defined).
OpenFAST encountered an error at simulation time 1.575 of 3600 seconds.
Simulation error level: FATAL ERROR
I am not sure why this is so. I have turned off HydroDyn and MoorDyn for wind only case. When I ran the wind and wave case the model worked fine, so not sure.
Let me know if you have any ideas about problem 1 and this new problem, problem no. 2.
Thank you.
Regards,
AOAW