# Eddy viscosity formulation

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 November 7, 2008, 09:16 Eddy viscosity formulation #1 Raja Guest   Posts: n/a 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...

 November 7, 2008, 09:57 Re: Eddy viscosity formulation #2 Pascal Guest   Posts: n/a 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.

 November 7, 2008, 10:57 Re: Eddy viscosity formulation #3 Friend Guest   Posts: n/a 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.

 November 8, 2008, 06:59 Re: Eddy viscosity formulation #4 Raja Guest   Posts: n/a 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

 November 11, 2008, 05:32 Re: Eddy viscosity formulation #5 Rami Guest   Posts: n/a The link you supplied uses the kinematic viscosity. Maybe FLUENT reference uses dynamic viscosity?

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