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linnemann March 13, 2012 03:24

Possible to make a thread sticky
Hi moderators,

Is it possible to make a thread sticky?

I would like to have a sticky thread that describes best how to get help on the forum what kind of info would be helpful etc.

Right now the threads often have too little info to help users sufficiently and maybe a sticky on the main forum can help remedy some of this. I know that there was a previous post about this some time ago, but now I cant find it.

Would be nice to have at the top of the main forum at all times.


akidess March 13, 2012 04:01

This is the old thread you are referring to:

The way to go is to draft a post with the contents of the sticky, and then ask a moderator to promote it.

- Anton

akidess March 15, 2012 06:05

I have restructured the guide on the wiki:

Any comments?

Copy of the text for convienence:

HowTo Get Help On The Message Board
... or the importance of precise posting

Questions on the message board are answered by volunteers. So
* you can't expect to get an answer to every question (sometimes no one knows the answer)
* but you can increase the probability to get an answer by using the following guidelines

And always remember: '''The difficult part about science is asking the right questions'''

'''Before posting - do your homework'''
* Give the person that should answer your question the feeling that you've invested at least as much time in it (formulation, previous research ...) as you expect her to invest in the answer. As said above: people are answering in their spare time.
* Use the search-function of the message-board (or google with "") to see if somebody had this problem before. Let people know what you have found and why it didn't help. Show that you have though about your problem.
* If you have the feeling that your problem is unique/new: start a new thread

* Using an identifiable name is appreciated, and will get you respect in this community
* If you start a new thread give it a meaningful title (threads like "Hlp plz!" or "I'm a newbie" are very unlikely to draw attention)
* Don't cross-post. Posting the same question (even with small variations) to various threads doesn't increase the likelihood of it being answered (on the contrary)
* Don't hijack threads. Just because people discuss the convergence of interFoam in a given thread doesn't mean that this is the place to talk about correct boundary conditions for the <tt>alpha</tt>-field
* Use english
* Be polite
* Be precise, but be brief. Make sure a large audience can understand your problem. Include relevant information like
** Problem description: What's your problem? What have you tried to fix your problem, and why hasn't it worked?
** Relevant output. Clip it to the relevant parts (it is very unlikely that someone will answer a posting that includes 123 time-steps)
** OpenFOAM-version and specific solver
*** If your problem is related to compiling source code, always report the first compiler error. C-compilers will report multiple errors at once.
*** If you have a problem with solver convergence, be sure to let people know about the numerical schemes you are using and the solver settings

''Disclaimer: This is just a personal opinion and not the official policy of the Message-Board''

linnemann March 15, 2012 06:39

Hi looks good.

If I get time I will see if I can build on that to give some examples on how to make a "good" post.

Can you make a thread with the link to the wiki and have it made sticky?

Otherwise it will drown on all the other posts.


akidess March 16, 2012 06:27

I think the sticky post should have it all written out; a link to the wiki doesn't cut it. So I'd like to get more feedback, and only once the sticky note has been determined good enough ask a moderator to make it sticky.

- Anton

wyldckat March 18, 2012 17:04

Greetings to all!

I changed the "" reference to a click-able link, in an attempt to be "dummy proof". The problem is if this is future proof or not :(

I also wanted to add a line for people to try and avoid reviving ancient threads, since it'll be unlikely for anyone on that thread to answer... but I tend to run long with my sentences :rolleyes:

Another important line is that people should use the [CODE] markers. Example:
HTML Code:

Place here a piece of code or output

Yet another one is: always try to post on a relevant sub-forum! Posting on the main OpenFOAM forum will make it harder for everyone in the long run.

Last but not least - if you want to understand better how to use the Forum, read the Frequently Asked Questions page:

Best regards,

linnemann March 19, 2012 04:54

An example on how to get proper help following the guideline shown.

I will try to give an example taken purely from my own imagination that show the kind of info I would like in order to help people.

=== 0 ===
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 picture/file makes it a lot easier to share files/pics or the full case.

=== 1 ===

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

simpleFoam pipe case diverges

What this little information tells us is that the solver is simpleFoam, the geometry is a pipe and we know that the problem is that it diverges.

=== 2 ===
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 when trying to visualise the case in others brains.
The "a picture says more than a thousand words" quote springs to mind here

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

Also the first info you need to give is the output from checkMesh put into a log file


checkMesh > checkMesh.log

Ok now people know that you have a pipe with two bends and that the mesh is fully structured (paraview shows some as tets, but that is a render issue). The dimensions of the pipe is also known now. Also from the header files people know that you are using OpenFOAM version 2.1.x, this is relevant since there can be some bugs in the version used.

=== 3 ===
Ok now we are ready to start identifying the problem.
You know that you have divergence problems and if you have opened just one book about CFD, you know that stability is related 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 will allow people to see if you have the correct setup for the type of case/mesh you have.

=== 4 ===
Also some good information to give is the output from the terminal, but please don't post 10+ iterations. Post only the relevant bits, for example the 2-3 iterations where the solver start to diverge. Another options would be to give the log file as a upload/link. The output can be put into a file using.


simpleFoam > simpleFoam.log 2>&1
Below is an example of two iterations, they don't diverge but you get the drift.


Time = 11

smoothSolver:  Solving for Ux, Initial residual = 0.0394701, Final residual = 0.00283316, No Iterations 4
smoothSolver:  Solving for Uy, Initial residual = 0.0244406, Final residual = 0.00163773, No Iterations 4
smoothSolver:  Solving for Uz, Initial residual = 0.211626, Final residual = 0.0144428, No Iterations 4
GAMG:  Solving for p, Initial residual = 0.332445, Final residual = 0.0124884, No Iterations 7
time step continuity errors : sum local = 0.0803619, global = 0.0111056, cumulative = 0.0907056
smoothSolver:  Solving for epsilon, Initial residual = 0.0137779, Final residual = 0.000915039, No Iterations 3
smoothSolver:  Solving for k, Initial residual = 0.0205267, Final residual = 0.00103642, No Iterations 4
ExecutionTime = 6.07 s  ClockTime = 6 s

Time = 12

smoothSolver:  Solving for Ux, Initial residual = 0.0966665, Final residual = 0.00756253, No Iterations 4
smoothSolver:  Solving for Uy, Initial residual = 0.103096, Final residual = 0.00828772, No Iterations 4
smoothSolver:  Solving for Uz, Initial residual = 0.122408, Final residual = 0.00767765, No Iterations 4
GAMG:  Solving for p, Initial residual = 0.181939, Final residual = 0.00707472, No Iterations 5
time step continuity errors : sum local = 0.0780837, global = -0.0134194, cumulative = 0.0772862
smoothSolver:  Solving for epsilon, Initial residual = 0.0127022, Final residual = 0.000977349, No Iterations 3
smoothSolver:  Solving for k, Initial residual = 0.0222577, Final residual = 0.00121352, No Iterations 4
ExecutionTime = 6.46 s  ClockTime = 7 s

=== 5 ===
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 that if you follow this simple guide you will get the help you need.

akidess March 20, 2012 07:52

Great comments, thanks to both of you! I'll try to incorporate it into the wiki article later this week.

- A

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