How to give enough information to get Help (Cfdonline website reprint)

An example-to-get proper help following the guideline shown.

I'll try to give a example taken purely from my own imagination so show the kind of info I would like in order to Hel P people.

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Prepare for getting help. Cfd-online does not provide large filesize uploads so registering a Dropbox/box account and use a public link to the PICTU Re/file makes it a lot easier to share files/pics or the full case.

1 ////////cfdoline does not provide uploading of large files, so it is recommended to upload to other websites and use public links to share the code .

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First give it a relevant name in the title of the thread

Simplefoam Pipe Case diverges

What's this little information tells us are that the Solver are Simplefoam, the geometry is a pipe and we know that the proble M is the IT diverges.

////////////////// //This topic provides information on: Simplefoam solver, pipe shape, PDE divergence   

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Second give a sketch of the geometry, a screendump of the mesh and maybe even a cut through the mesh. ParaView and the Clip filter works good here.
This helps immensely if trying to visualise the case in others brains.
The "a picture says more than a thousand words" quote springs

Below is an example of a picture inserted using a public link from Dropbox.



Also the first info need to give are the output from Checkmesh put into a log file

Checkmesh > CheckMesh.log

Ok now people know so you had a pipe with both bends and that the mesh is fully structured (ParaView shows some as tets, But that's a render issue). The dimensions of the pipe is also known now. Also from the headers files people know that's the using OpenFOAM version 2.1.x, this was relevant since there can be some Bugs in the version used.

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Ok Now we is ready to start identifying the problem.
You know the divergence problems and if you have opened just one book about CFD, you know that stability are RelA Ted to a number of things.

• Mesh, We get good output from checkmesh so thats ok
• Solver, this we get from the Fvsolution file so upload/link that
• Schemes, from the Fvschemes file so upload/link that

This would allow people to see if you have the correct setup for the type of Case/mesh.

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Also some good information to give are the output from the terminal, and please don ' t post + + iterations. Post only is the relevant bits, for example the 2-3 iterations where the Solver start to diverge. Another options would is to give the log file as a upload/link. The output can is put into a file using.

2>&1

Below is an example of both iterations, they don ' t diverge but you get the drift.

Time = Onesmoothsolver:solving forUx, Initial residual =0.0394701, Final residual =0.00283316, No iterations4smoothsolver:solving forUy, Initial residual =0.0244406, Final residual =0.00163773, No iterations4smoothsolver:solving forUz, Initial residual =0.211626, Final residual =0.0144428, No iterations4gamg:solving forp, Initial residual =0.332445, Final residual =0.0124884, No iterations7Time Step Continuity errors:sum Local=0.0803619,Global=0.0111056, Cumulative =0.0907056smoothsolver:solving forEpsilon, Initial residual =0.0137779, Final residual =0.000915039, No iterations3smoothsolver:solving forK, Initial residual =0.0205267, Final residual =0.00103642, No iterations4ExecutionTime=6.07s clocktime =6stime= Asmoothsolver:solving forUx, Initial residual =0.0966665, Final residual =0.00756253, No iterations4smoothsolver:solving forUy, Initial residual =0.103096, Final residual =0.00828772, No iterations4smoothsolver:solving forUz, Initial residual =0.122408, Final residual =0.00767765, No iterations4gamg:solving forp, Initial residual =0.181939, Final residual =0.00707472, No iterations5Time Step Continuity errors:sum Local=0.0780837,Global= -0.0134194, Cumulative =0.0772862smoothsolver:solving forEpsilon, Initial residual =0.0127022, Final residual =0.000977349, No iterations3smoothsolver:solving forK, Initial residual =0.0222577, Final residual =0.00121352, No iterations4ExecutionTime=6.46s clocktime =7S

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This might seem like a lot of work, but if you want people to invest time on you, you must invest at least as much time in Asking the right question and give sufficient input to allow people to help you.

I ' m sure so if you follow this and you'll get the help you need.

How to give enough information to get Help (Cfdonline website reprint)