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-   -   Favre averaged values (https://www.cfd-online.com/Forums/openfoam-solving/60149-favre-averaged-values.html)

 chris1980 June 22, 2006 09:27

I want to do RANS with variabl

I want to do RANS with variable density. The governing equations for my problem known but I was wondering how to treat the favre averaged values!

- Are the variables automatically favre averaged when using a compressible RANS-model?

- When the solver computes i.e. k,epsilon ... are these the Favre averged values which I get back?

As you can see I am a little bit confused with these averaging things.

 grtabor June 22, 2006 10:13

Yes, and yes. The point of

Yes, and yes.

The point of Favre averaging is that it is a mathematical trick designed to get us back to the same form of the equations. We _know_ how to solve the NSE in the form

ddt(rho u) + div(rho u u) = ...

When we average this equation /\ we get

ddt(/rho u \) + ....

Favre averaging allows us to split /rho u\ into separate variables, getting back to where we started again. So, yes; when using a compressible RANS model, the variables will be by definition assumed to be Favre averaged.

Gavin

 ayannath23 July 14, 2012 21:29

Favre or RANS averaged equations are used in incompresible reacting flow ?

I'm simulating incompresible reacting flow case where RSM is used as turbulence model. I have doubt about what fluent is actually solving for my case. Whether Favre-averaged NSE or RANS averaged NSE.

Can anybody help ?

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