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Old   November 7, 2008, 08:16
Default Eddy viscosity formulation
  #1
Raja
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Dear all, I found the formula for Eddy viscosity in FLUENT manual is

DENSITY * C * KineticEnergy*KineticEnergy / DissipationRate.

Constant C=0.09

But, in another literature for the same Standard K-E turbulence model, they have not including the Density in the above expression. In which case this formula will differ ??

If you see the following link, here, they have not included the Density part. http://w3.gre.ac.uk/~physica/phy3.00/theory/node152.htm

Kindly provide the clear idea regarding this issue. Thank you very much Raja...
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Old   November 7, 2008, 08:57
Default Re: Eddy viscosity formulation
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Pascal
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Hi Raja,

I havent read the Fluent manual, but I guess Fluent is not wrong, and the article neither!

I would use the definition of your article, this is the one I have learnt. I guess it is just that in Fluent manual, they don't use rho as a factor in the equation and use it for each term.

Just check that K and e equation are the same in Fluent manual and in your article (or in your course notes) for your understanding.
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Old   November 7, 2008, 09:57
Default Re: Eddy viscosity formulation
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Friend
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That is because the kinetic energy in Fluent is defined per unit mass. You need to cross check that as in the end they should be having similar unit.
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Old   November 8, 2008, 05:59
Default Re: Eddy viscosity formulation
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Raja
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Hi Pascal, thank you very much for your guidence. Yes, what you said is right. In, K and E equations, they(FLUENT) have included Density term, where as in my work, we have not included the Density term. Again, thank you very much.

Raja
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Old   November 11, 2008, 04:32
Default Re: Eddy viscosity formulation
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Rami
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The link you supplied uses the kinematic viscosity. Maybe FLUENT reference uses dynamic viscosity?
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