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CFX Solver manager runs for a long time!!

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Old   May 14, 2013, 03:23
Smile CFX Solver manager runs for a long time!!
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Hello Guys,
I cannot understand why the solver takes a long time (more than 2 hours) in the running process and how I can know whether the running is converging or diverging
PS: I am using an SST model with a steady state solution.
Thank you
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Old   May 14, 2013, 04:23
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Matthias Voß
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you can look at the convergence history by looking at the graphs in the solver monitor. (right click on Solution in WB2.0 or opening the CFX-Launcher-->Solver--> Monitor Run in Progress)
since you state 2h is a long time to run i assume you´re fairly new to this field.
for the future: please provide just a little bit more info.
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Old   May 14, 2013, 04:35
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Thanks,
Absolutely! I´m new to ANSYS
For more info: I am working on a cooling technique using staggered Pin fins within a rectangular duct.
I have to simulate the flow field.
Then, I should calculate the friction factor (from the pressure drop) and the heat transfer coefficient.
PS: I am using CFX in stand-alone mode not the WB

Last edited by Amoul; May 14, 2013 at 09:02.
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Old   May 14, 2013, 04:39
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you should definitely do some of the basic tutorials before starting your simulation. Check your convergence settings. If the simulations runs for several hours WITHOUT reaching the BASIC convergence settings, then there´s smth. wrong. Mesh, TimeStep, BC.
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Old   May 14, 2013, 04:49
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it is actually my question: How can I check the convergence settings?
I have already done basic tutorials: they do not explain how to check this. They directly move on to the CFX post without explaining the results of CFX solver manager :/
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Old   May 14, 2013, 06:20
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2 hours?

I've heard of people who run simulations for 3 weeks on 24 cores!
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Old   May 14, 2013, 06:41
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please post a pic of your solver monitors. this will make it way easier.
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Old   May 14, 2013, 08:20
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Yes, 2 hours is a bit laughable - I have run simulations which went for 6 weeks.

But you always approach big simulations with care. Do all your homework first to make sure you are not wasting your time. Run a small simulation to check things are working. Do all the necessary sensitivity checks so you know you will get it right the first time. And do lots of practise on smaller simulations before you commit to the big simulations.
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Old   May 14, 2013, 08:42
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Please find here attached my solver window.
It is the simulation of the flow within a rectangular duct containing staggered pin fins.
*Model: SST
*Steady state solution
*5% turbulence intensity


Would you please tell me how could I check the sensitivity and the convergence settings of my solver knowing that i am using CFX stand-alone mode?
Thank you!

PS: Actually, it takes much more than 2 hours (maybe days, who knows ´cause I have not waited till the solver stops because I don t know how I can be sure that it is running correctly (it s converging) )
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Last edited by Amoul; May 14, 2013 at 08:58.
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Old   May 14, 2013, 12:01
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it is converged for basic tasks like getting rough results and initial conditions fo furture runs .10e-4 is enough for this purpuse but to have accurate results you whould let solver goes for RMS bellow 10e-5 or10e-6
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Old   May 14, 2013, 20:10
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As Hamed has said, your simulation has converged a little bit but then stalled. This FAQ discusses what to consider next: http://www.cfd-online.com/Wiki/Ansys...gence_criteria
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Old   May 15, 2013, 04:05
Wink Thank you!
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I would like to thank all of you for your help! I appreciate this
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