CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   Two Questions for Turbulence Modeling (http://www.cfd-online.com/Forums/main/103290-two-questions-turbulence-modeling.html)

mohammad.sarfaraz June 16, 2012 03:09

Two Questions for Turbulence Modeling
 
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.

Regards,

mb.pejvak June 17, 2012 00:43

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.

chris85 June 18, 2012 06:35

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.


All times are GMT -4. The time now is 06:15.