How do I run OpenFAST

Wind & Water Computer-Aided Engineering Software Tools
21

Emmanuel:
I will give it a try and see. Sorry for the delayed response. Did not realize you had responded.

Thank you.

Regards,
AOAW

22

Jason:
Is there a way to find out if a model in OpenFAST converges? Kind of similar to CFD, for example, where the mesh refinement can alter accuracy of results/help one to determine if model converges.

Regards,
AOAW

23

Dear Andre.

I’m not sure I fully understand your question, but of course, the OpenFAST solution likely depends on the discretization used, including the spatial discretization of the structural, aerodynamic, and hydrodynamic nodes and the time steps. When setting up a model, it is important to set appropriate discretizations so as to achieve the precision desired.

Best regards.

24

Jason:
Thank you.
I think you got it. You said, “When setting up a model, it is important to set appropriate discretizations so as to achieve the precision desired.”

[b]Could you please help me to know how these discretizations set in OpenFAST? In order words, what are the variables used to discretize?

Regards,[/b]
AOAW

25

Dear Andre,

This would be:

in the OpenFAST primary input file:

  • the glue code (coupling) time step (DT)

in the ElastoDyn module:

  • the structural time step (DT)
  • the number of blade and tower structural analysis nodes (BldNodes, TwrNodes)

in the AeroDyn module:

  • the aerodynamic time step (DTAero)
  • the number and location of the blade aerodynamic analysis nodes (NumBlNds, BlSpn)
  • the number and location of the tower aerodynamic analysis nodes (NumTwrNds, TwrElev)

etc. for other modules like HydroDyn, SubDyn, and MoorDyn.

Best regards,

26

Many thanks Jason.

Regards,
AOAW

27

Hi Jason:
I would like to find out if OpenFAST can be used to investigate the performance of different types of mooring systems under extreme wind and wave loads. Say, a fibre rope system and the regular chain type mooring system, considering fatigue and breaking loads. I know the fibre rope would exhibit non-linear behaviour unlike the chain type mooring so would like to know if that can be modelled or would I have to assume that the rope is linear in OpenFAST.

Regards,
AOAW

28

Hi Andre,

The MoorDyn model in OpenFAST has some features for nonlinear mooring elasticity that are nearing completion. They are part of a set of new features for MoorDyn v2, which we currently plan to include in the next release of OpenFAST, v3.1. There will be an option for nonlinear tension-strain relations, and an option for a simple viscoelastic model that has different stiffnesses for low vs. high frequencies. We’ll share more information about the features when the release happens.

Matt

29

Thanks and noted @Matthew.Hall.

Regards,
AOAW

30

Hi @Jason.Jonkman /@Matthew.Hall I am still trying to run OpenFAST from MATLAB as I now need to run multiples simulations. However, the runFAST script is still giving me an error that the simulation failed to run as I reported previously.

I am now trying to use Visual Studio 2019 and Intel Parallel Studio Xe 2019 to compile and create “FAST_SFunc.mexw64” (see first page of instructions attached) so that I can run in MATLAB in the same way it was done in FAST. However, I get some errors which I have attached.

OpenFAST_Simulink-1
OpenFAST_Simulink-11700×2200 284 KB

VS_IntelParallelErrors-1
VS_IntelParallelErrors-11654×2339 202 KB

VS_IntelParallelErrors-2
VS_IntelParallelErrors-21654×2339 224 KB

VS_IntelParallelErrors-3
VS_IntelParallelErrors-31654×2339 224 KB

VS_IntelParallelErrors-4
VS_IntelParallelErrors-41654×2339 232 KB

VS_IntelParallelErrors-5
VS_IntelParallelErrors-51654×2339 112 KB

Do you have any idea what is causing these errors and how I could solve?

Thank you.

Regards,
AOAW

31

Hi @Jason.Jonkman:
Please disregard previous query. I have made some progress. However, when I run in MATLAB I am getting the following error. The command I use to run in MATLAB is
dos(['openfast ', fname]), where fname is the .fst file and the openfast links to a batch file with the .exe location.
The error I get is shown below:
**FAST_InitializeAll:FAST_Init:FAST_ReadPrimaryFile:Invalid numerical input for file **
“IEA-15-240-RWT-UMaineSemi.fst” occurred while trying to read MHK.

a OpenFAST encountered an error during module initialization. **
** Simulation error level: FATAL ERROR

Aborting OpenFAST.
ans = 1

I am not sure what the MHK issue could be. Is there something that I need to change in input file for it to read MHK?

Thank you.

Regards,
AOAW

32

Dear @Andre.White,

MHK and other inputs were added in OpenFAST v3.1. It looks you are running with a version of OpenFAST that is newer than your input files are formatted for. Updating the input files to the newer format should solve the problem. For more information see the API documentation: 4.1.2. API changes between versions — OpenFAST v3.3.0 documentation.

Best regards,

33

Hi @Jason.Jonkman many thanks. I will make the amendments.
A very splendid Easter holiday to you and family and the rest of your team.

Regards,
AOAW

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