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What means "bounding epsilon"?

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Old   October 25, 2012, 05:15
Default What means "bounding epsilon"?
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Mattia
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Hello, I have an easy question. I don't understand what means "bounding epsilon" or k, during running of simpleFoam. Is there someone that can tell me what it means?

Thanks a lot.
Best Regards.

Mattia
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Old   October 25, 2012, 09:51
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Simone
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Hi Mattia,
I have experienced the same problems. What I can suggest you is to evaluate carefully the initial/boundary values for your turbulent variables, and maybe you could have a look to your fvSchemes and fvSolution files.

More precisely:
- in fvSchemes you could use upwind scheme for the terms involving your turbulent variables;
- in fvSolution have a look to the tolerances you use for your turbulent variables and to the relaxation factors (maybe you could be a little more conservative and use a lower value of relaxation factor)

With these modifications my simulation has not diverged any more.

Best regards
Simone
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Old   October 26, 2012, 08:10
Default Bounding Turbulence variables
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Goncalo Pedro
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Hi Mattia

The solver is reporting high or low values of a turbulence variable. It is typically indicative of some instability within the solution.

As the post above mentions there are a couple of ways to deal with it. In my experience it often comes down to mesh quality. Maybe lack of refinement in certain areas with high gradients etc.

Sometimes these bounded values go away as the solution converges.

Goncalo
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Old   October 29, 2012, 09:59
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Mattia
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Thanks batta31 and gonpe for the replies.

Best regards.
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