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by Jason.Jonkman
Mon Jun 14, 2021 4:51 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Hydrodynamic coefficients HELP!
Replies: 30
Views: 1230

Re: Hydrodynamic coefficients HELP!

Dear Bartsoz, The off-diagonal terms come from the fact that the mooring line fairleads are not placed at (0,0,0). So, the force caused by translation will result in moment; likewise rotation will cause a force. The sign is based on the coordinate system with surge-pitch coupling the opposite sign (...
by Jason.Jonkman
Mon Jun 14, 2021 3:42 pm
Forum: Computer-Aided Engineering Software Tools
Topic: ServoDyn error
Replies: 1
Views: 16

Re: ServoDyn error

Dear Bruce, Not all precompiled binary executables of OpenFAST require the Intel redistributable libraries; the ones that do were built to require dynamic libraries from Intel rather than being compiled with Intel static libraries. I don't recall what OpenFAST v1.0.0 requires, but regardless, I woul...
by Jason.Jonkman
Mon Jun 14, 2021 3:30 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Direct drive generator and edgewise bending of the blades
Replies: 4
Views: 52

Re: Direct drive generator and edgewise bending of the blades

Dear Bartosz, I agree with your interpretation of the drivetrain DOF in the ElastoDyn module of FAST / OpenFAST. And I agree that for direct-drive wind turbines, with a short, stiff shaft, that the drivetrain DOF can be disabled. I'm not sure which baseline controller you are referring to, but a low...
by Jason.Jonkman
Mon Jun 14, 2021 3:17 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Two-blades wind turbine
Replies: 5
Views: 84

Re: Two-blades wind turbine

Dear Tianhui.Liu, I'm not sure I know the history all models in the OpenFAST r-test are set up the way the are, but they are more set up as examples that can be used to test the various functionality of OpenFAST. Regarding AWT_YFree_WTurb, this model is set up with GenDOF = False and RotSpeed = 53.3...
by Jason.Jonkman
Fri Jun 11, 2021 10:55 am
Forum: Computer-Aided Engineering Software Tools
Topic: FAST theory manual
Replies: 375
Views: 82724

Re: FAST theory manual

Sent.
by Jason.Jonkman
Fri Jun 11, 2021 10:34 am
Forum: Computer-Aided Engineering Software Tools
Topic: Inhomogen turbulent windfield
Replies: 11
Views: 2785

Re: Inhomogen turbulent windfield

Dear Jian,

The Intel command prompt can be opened by clicking on the associated link from the Start menu:
IntelCommandPrompt_StartMenu.png
IntelCommandPrompt_StartMenu.png (75.94 KiB) Viewed 36 times

When opened, the Intel command prompt looks like this:
IntelCommandPrompt.png
IntelCommandPrompt.png (14.82 KiB) Viewed 36 times

Best regards,
by Jason.Jonkman
Fri Jun 11, 2021 10:28 am
Forum: Inflow Turbulence
Topic: Turbsim for Class IV from IEC 61400-1 2nd edition
Replies: 9
Views: 3857

Re: Turbsim for Class IV from IEC 61400-1 2nd edition

Dear Jian, My answers to questions 1-3 are yes. Regarding (1), I would say that the IEC 61400-3 does not recommend that the equation sigma_1=V_hub/ln(Z_hub/Z_0)+1.28*1.44*I_15 be used to define the design turbulence level; instead, the equations from IEC 61400-1 define that (same for land and offsho...
by Jason.Jonkman
Fri Jun 11, 2021 10:24 am
Forum: Computer-Aided Engineering Software Tools
Topic: Aerodyn standalone version
Replies: 7
Views: 80

Re: Aerodyn standalone version

Dear Florence, Downloading OpenFAST from https://github.com/OpenFAST/openfast should give you OpenFAST v2.6 as of now, assuming that you've selected the main branch. The AeroDyn input file available from readthedocs (https://openfast.readthedocs.io/en/main/_downloads/1270204a8cbfec62f2a41a8d746a9ce6...
by Jason.Jonkman
Fri Jun 11, 2021 9:04 am
Forum: Computer-Aided Engineering Software Tools
Topic: Error during linearization with VolturnUS-S
Replies: 3
Views: 24

Re: Error during linearization with VolturnUS-S

Dear Andre, The "nodal output" warning will not effect the simulation results; you can ignore the warning. Otherwise, the error messages are pointing to the solution: ⋅ Set WvDiffQTF = False -- You cannot linearize HydroDyn with 2nd-order wave kinematics enabled ⋅ Set D...
by Jason.Jonkman
Fri Jun 11, 2021 8:10 am
Forum: Computer-Aided Engineering Software Tools
Topic: Gain Scheduling
Replies: 27
Views: 13536

Re: Gain Scheduling

Dear Adèle, When the rotor is spinning, I would not recommend using NLinTimes = 1. When the rotor is spinning, I would generally recommend linearizing every 10-degrees of azimuth, so, NLinTimes, which is the number of times to linearize in one rotor revolution should be set to 36. NLinTimes = 1 is m...
by Jason.Jonkman
Thu Jun 10, 2021 5:52 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Aerodyn standalone version
Replies: 7
Views: 80

Re: Aerodyn standalone version

Dear Florence, Your error is pointing to a problem with your input file format. Even if you are not modeling an MHK rotor, you still must have the CavitCheck, Patm, Pvap, and FluidDepth inputs in your AeroDyn input file associated with OpenFAST v2.1, which looks to be the version you are running. As...
by Jason.Jonkman
Thu Jun 10, 2021 1:38 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Modelling Tower
Replies: 12
Views: 1253

Re: Modelling Tower

I've now raised the inability of OpenFAST v2.6 to visualize offshore support structures in the following OpenFAST github issue: https://github.com/OpenFAST/openfast/issues/776.
by Jason.Jonkman
Thu Jun 10, 2021 10:48 am
Forum: Computer-Aided Engineering Software Tools
Topic: Changing water depth for DeepCwind Model etc.
Replies: 37
Views: 2359

Re: Changing water depth for DeepCwind Model etc.

Dear Andre,

The model you running uses a steady, uniform wind speed of 8 m/s (also seen in your results in column B), which is below rated, where blade-pitch control is not active. The blade-pitch angles should remain at 0deg for this simulation.

Best regards,
by Jason.Jonkman
Thu Jun 10, 2021 10:39 am
Forum: Computer-Aided Engineering Software Tools
Topic: FAST v8 "Mach number exceeds 1.0" for some wind cases
Replies: 20
Views: 4850

Re: FAST v8 "Mach number exceeds 1.0" for some wind cases

Dear Raúl, Well, it looks like your model has gone unstable in the platform. The exact error that aborts the simulation (whether it be high Mach number or a node passing the boundaries of the TurbSim grid) is determined by which features you've enabled in the model, but is probably irrelevant. It is...
by Jason.Jonkman
Thu Jun 10, 2021 10:23 am
Forum: General
Topic: Platform Additional Stiffness and Damping
Replies: 21
Views: 4132

Re: Platform Additional Stiffness and Damping

Dear Brendan, I believe the equation in HydroDyn is correct because this is the inertia about the node at the end of the cylinder, not the inertia about the center of mass of the cylinder. Before the improvements to HydroDyn in v2.6, the inertia of the filled fluid in HydroDyn assumed the filled flu...

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