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-   -   K epsilon values (http://www.cfd-online.com/Forums/fluent/49333-k-epsilon-values.html)

Adrian September 24, 2008 10:18

K epsilon values
 
Hi Fluent Userīs Iīm working with cars and I would like to know what values do I have to put in inlet and outlet bondaries when fluent ask me K epsilon values thanks

Saintest September 25, 2008 08:04

Re: K epsilon values
 
you can get the K value accoding the following equation. Tu=sqrt(2k/3)/V_far sorry I don't kown how to set the epsilon value for car!you can try the default value. it bother me for long time how to set the epsilon value and omega value for k-e and k-o model.

Adrian September 25, 2008 09:12

Thank Saintest
 
Thank Saintest I will try and I tell you later thank you again Regars Adria

John S September 26, 2008 11:16

Re: Thank Saintest
 
Computing values for k and epsilon is not a simple task and more often than not you will have to guess for the initial solution. You can use the equation given already to guess an initial value for k and a good initial guess for epsilon can be made using e = .9k^(3/2) / l; where l is your turbulent mixing length. The mixing length can be estimated using l = K*(1-e^(-y+/A+)*y; where K is the von Karman constant ~.41, and A+, for your case, would be 26 I believe (zero streamwise pressure gradient flow).


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