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,

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.

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.