AeroDyn Error Code: FF wind array exhausted

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John.Chang
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Joined: Fri Jul 19, 2019 12:34 am
Organization: self
Location: Germany

AeroDyn Error Code: FF wind array exhausted

Postby John.Chang » Thu Aug 29, 2019 8:39 am

Dear ladies and gentlemen,
I am having trouble finding the problem with my simulation. I think, according to the error massage, the problem lies in AeroDyn. However, I can’t figure out what exactly the problem is.
I am trying to simulate DLC on a floating offshore wind turbine (5 MW NREL reference wind turbine for offshore system & semi-submersible floating system for phase II of OC4).
Wind speed: 12 m/s, hub height 100 m

The error code are as followed:
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INFO: Aerodynamic loads calculated using AeroDyn (v13.00.00a-bjj, 31-Mar-2010).
Heading of the AeroDyn input file: NREL 5.0 MW offshore baseline aerodynamic input properties; Compatible with AeroDyn v13
Assuming E:/LCT – Offshore / 03_example_load_calculation / DLC11 / DLC11_WS0012_WD0000_UF0008_HE0200_TS0007 / mbs_db_aerodyn / AeroDyn_PP / IEC2A_NTM_WS0012_WD0000_UF0008_HE0200_TS0007.wnd is a binary FF wind file.
Reading a 26x26 grid (140 m wide, 30 m to 170 m above ground) with a characteristic wind speed of 12 m/s.
Processed 12634 time steps of 20-Hz full-field data (631.65 seconds).
Error: FF wind array was exhausted at 0 seconds (trying to access data at -3.0427 seconds).
Error getting velocity in AeroDyn/AD_WindVelocityWithDisturbance().
FATAL ERROR in AeroDyn library!

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For the DLC 1.1 analysis with the wind speed of 3, 6, 9 m/s, the simulation ran without any trouble. However, I am experiencing the same fatal error as above in the simulation with the wind speed 12, 15, 18, 21, 24 m/s.

After going through the forum I assumed, the grid of the find field was the problem. But it did not correct my problem.

Your advice will be highly valued.
Thank you.

Sincerely,

John Chang

Jason.Jonkman
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Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
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Re: AeroDyn Error Code: FF wind array exhausted

Postby Jason.Jonkman » Thu Aug 29, 2019 4:43 pm

Dear John,

Do you receive this error right away at time zero? Is your initial surge displacement far downwind, where perhaps there is no wind defined in the simulation?

I'm not sure if you are using TurbSim to generate the turbulent wind data file or not, but you may be interested in the UsableTime = "ALL" option of TurbSim, which ensures that the turbulent wind data generated is periodic, and so, FAST assumes that the wind data extends effectively forever in the along-wind direction. I would not expect you to receive the error you are receiving when using this option.

I also noticed that you are using AeroDyn v13, which presumably means that you are using FAST v7. The floating wind modeling capability has been drastically improved in newer versions of FAST e.g. FAST v8 or OpenFAST. I would suggest upgrading.

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


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