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K epsilon values

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Old   September 24, 2008, 10:18
Default K epsilon values
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Adrian
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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
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Old   September 25, 2008, 08:04
Default Re: K epsilon values
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Saintest
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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.
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Old   September 25, 2008, 09:12
Default Thank Saintest
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Adrian
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Thank Saintest I will try and I tell you later thank you again Regars Adria
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Old   September 26, 2008, 11:16
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John S
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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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