[lscleaver]

Hi
Im trying to use a modified RNG model reccommended by Reboud et al. i don't know how to modify the formulas in CFX. so how would i do this?



Many thanks
Luke

[Opaque]

You are trying to modify the RNG model using information from the k-w model. That is a risky proposition without careful validation.

Or, you mean to modify the k-w model as suggested (assuming the authors did the proper validation)

[lscleaver]

Thanks for replying
Used wrong image as thats for SST
this is what i need to modify RNG with.

[Opaque]

After selecting the RNG model, open the Advanced Controls for the turbulence model setup, and overwrite the Eddy Viscosity value by your own CEL expression.

Hope the above helps,

[lscleaver]

Very much so
thank you

[lscleaver]

Does this look right to you?

[Opaque]

Is your model single phase multicomponent material, or multiphase flow ?

For a single phase multicomponent material, the expression seems correct.

For a multiphase flow model, it is not clear what "density" means. If you intend to be the volume fraction weighted density, I would write it explicitly. That is, MyMixtureDensity = WaterVapour.Density * WaterVapour.Volume Fraction + ....

Hope the above helps,

[lscleaver]

It is a multiphase flow model and the "density" is the mixture of the 2 fluids.
Are you saying write a expression for that density? as
WaterVapour.Density*WaterVapour.VolumeFraction+Liq uidWater.Density*LiquidWater.Volume Fraction

[Opaque]

Correct.. Just in case the software assumes fluid phase.

[lscleaver]

Okay will try that