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how can i calculate k & epsilon values in OpenFOAM?

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Old   December 25, 2014, 05:42
Default how can i calculate k & epsilon values in OpenFOAM?
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Duong Tung
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Hello all,

I have some problems when i try to run pisoFoam (i want to use RANS to solve it) to solve elbow problem. You can see in the attached file the geometry and meshing

I can not calculate the values of k and epsilon to input into OpenFOAM (file k & epsilon in the 0 directory).
Can you help me to solve this problem and run it.
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Old   December 25, 2014, 06:59
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Derek Mitchell
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Quote:
Originally Posted by gnut1989 View Post
Hello all,

I have some problems when i try to run pisoFoam (i want to use RANS to solve it) to solve elbow problem. You can see in the attached file the geometry and meshing

I can not calculate the values of k and epsilon to input into OpenFOAM (file k & epsilon in the 0 directory).
Can you help me to solve this problem and run it.
Have you looked at page 40 in the OpenFOAM userguide.
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Old   December 25, 2014, 07:11
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Duong Tung
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Originally Posted by derekm View Post
Have you looked at page 40 in the OpenFOAM userguide.
Thanks Derekm very much!
I've seen it and tried to calculate.
The result for k = 1/2 (U'x^2 + U'y^2 + U'z^2) = 1/2 (0.04 + 1) = 0.52 m2 s-2
is it right or wrong?
You can help me calculate the value of epsilon????

Thanks again and hope that you merry christmas!!!!!

Duong Tung
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Old   December 25, 2014, 11:33
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Hasan K.J.
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Hey Duong Tung,

It is straight forward have a look at this and calculate your K, E, W etc.

http://www.cfd-online.com/Wiki/Turbu...ary_conditions

Happy simulation all the best,

Hasan K.J

Last edited by Alhasan; December 25, 2014 at 13:04.
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Old   December 25, 2014, 22:55
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Hey Duong Tung,

It is straight forward have a look at this and calculate your K, E, W etc.

http://www.cfd-online.com/Wiki/Turbu...ary_conditions

Happy simulation all the best,

Hasan K.J
Hello Hasan,

Thanks a lot for your suggestion! I have looked at the link and calculated in the attached excel file. Could you please check it for me?

I am still confused that I have two inlets (1 & 2) so i have to calculate two values for epsilon. Is it right or wrong???? And after inputting the value of k and epsilon into k & epsilon files at 0 directory in OpenFoam, I can run this problem????

Please help me to check it. Thank you very much!!!
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Old   December 25, 2014, 23:01
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Hasan K.J.
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Hey Duong Tung,

It looks like reasonable values to me, take it as a guidance value and run your simulations when you compare it with the experimental data you will get a better idea of where you stand !!

All the best,
Hasan K.J
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