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Fluent OpenFoam comparison kepsilon model

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Old   January 15, 2009, 12:20
Default Hi there I Can't match the
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Ali Mansouri
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Hi there

I Can't match the turbulent viscosity between
the Fluent - OpenFoam (used the same mesh),

my model is a 2D turbulent flow, the velocity field is almost the same...but k and epsilon are different,

any idea?

thank you,
Ali.
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Old   January 16, 2009, 00:21
Default check your turbulence paramete
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Prashant Ojha
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check your turbulence parameters at the boundaries.... further, I would like you to confirm if your solution has converged?

Your k and epsilon values should be properly initialized to reach convergence quicker. Please refer the user manual for initialization. Once convergence is achieved, results should be independent of the starting conditions.

Goodluck
Prashant
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Old   January 16, 2009, 11:58
Default Hi Prashant thanks for your
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Ali Mansouri
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Hi Prashant

thanks for your reply, yes my simulation is converged.

However the absolute values of both K and epslion are different from Fluent.

I estimated the initial values of K and epsilon as well...

is there any thing else that might cause the problem ? any other setting in OpenFoam?


Even my velocity field they are not exactly the same... should I get identical results ?


thanks!
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Old   January 19, 2009, 03:19
Default Hi Ali, last week in one of
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Markus Rehm
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Hi Ali,

last week in one of my simulations I noticed a limitation of k or epsilon (don't remember). So I changed the tolerance of the equations from 1e-7 to 1e-14 and the k and epsilon field changed considerably. I used realizable-k-eps.

Maybe that helps.

Regards, Markus.
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Old   January 19, 2009, 03:57
Default Hi Ali, A bit lateral to yo
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Gijsbert Wierink
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Hi Ali,

A bit lateral to your problem here, but perhaps useful for your research interest is that Hannu Ahlstedt presented a poster on k-epsilon comparison between Fluent and OpenFOAM at the 2008 OpenSource CFD conference in Berlin last December. The title is "Comparison of turbulence models in case of three-dimensional diffuser" by Aku Karvinen and Hannu Ahlstedt. On the website of the conference it says the proceedings will be online soon.

Regards, Gijsbert
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Regards, Gijs
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Old   January 19, 2009, 10:35
Default Hi, thanks Markus and Gijsb
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Ali Mansouri
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Hi,

thanks Markus and Gijsbert for your feedbacks,
much appreciated, Ali.
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