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Old   June 16, 2012, 03:09
Default Two Questions for Turbulence Modeling
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Mohammad Sarfaraz
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Hi all
I have 2 questions, which I would be thankful for recieving their answers:

1- When using k-epsilon model, what is the B.C. for the values of k and epsilon?
2- When adopting log. wall law, how does it work? give an example.

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Old   June 17, 2012, 00:43
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Mehdi
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I recommend you to read "An Introduction to Computational Fluid Dynamics" by Versteeg. it is good for start. and " Turbulence modeling for CFD" by Wilcox D.C. is very good in explanation of wall function.
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Old   June 18, 2012, 06:35
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Chris
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Also good book "Computational Methods for Fluid Dynamics" by Ferziger is good.

the k-epsilon model cant model the near wall region and thus a wall function is needed to solve the sub viscour near wall region. For this your meshing needs to be adequate so that y+ is between 30 and 300. This is what it is describing when mentioned log law.

Also your BC for the flow and values for k and epsilon will be dependant on the flow. See software help for equations which may be used to get these values.
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