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courant no increases rapidly

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Old   June 24, 2017, 02:11
Default courant no increases rapidly
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Bimalendu Mahapatra
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i am solving a flow over cylinder problem with fine mesh using pimplefoam.
the courant no increases rapidly after each time iteration and the simulation stops.
how to fix this problem.
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Old   June 24, 2017, 02:56
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Quote:
Originally Posted by pintu0101 View Post
i am solving a flow over cylinder problem with fine mesh using pimplefoam.
the courant no increases rapidly after each time iteration and the simulation stops.
how to fix this problem.
You have to lower the time step or use the Co control.
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Old   June 24, 2017, 08:12
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sir, thanks for the suggestion.
but we are using pimplefoam over icofoam so that we can give large time steps.
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Old   June 25, 2017, 07:07
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Quote:
Originally Posted by pintu0101 View Post
sir, thanks for the suggestion.
but we are using pimplefoam over icofoam so that we can give large time steps.
Pimplefoamhas the maxCo autoamtic:

set in controlDict

Code:
maxCo           0.1;
or any other value.
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Old   June 27, 2017, 05:26
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Hi all,

  • This is not a bug of openfaom so I will move this thread (just as an information)
  • pimpleFoam allows to have much larger values for the Courant number than 1 but you have to use the PIMPLE algorithm correct
  • If you don't know how to use it, you can find an explanation in my book (http://www.holzmann-cfd.de/index.php...s-and-openfoam)
  • Co > 1 requires the change of fvSolutions file in the manner I explained in the above book (its an own chapter)
  • In addition, your mesh can make problems


Good luck.
By the way, depending on the problem, you are not able to increase the Courant number as much as you want.
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