Talk:RNG k-epsilon model

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Hello I'm quite new in CFD

I'm reading about turbulence models and y+...

What does RNG mean?

I know that the difference between K-epsilon and RNG k-epsilon models are the constants in the transport equations but what is the purpose to change these variables and when we used each model?

Thanks

RNG means Renormalization Group Theory. It is a mathematical theory which can be used to derive a turbulence model which is similar to the k-epsilon model. When this was first done it was a kind of revolution that a mathematical theory could be used to derive this kind of turbulence model. It was done by Yakhot and Orzag. The exact formulation and constants in the RNG k-epsilon model is not the same as in the old k-epsilon models though. The RNG models have not been that much of a revolution though and they are not that frequently used today. Some people claim that for rotating flows RNG models are superior. I have tested a RNG k-epsilon model a few times and the only application where I noticed better results with it was in rotating cavities, but then it turned out to be more interesting to run transient and even DES/LES simulations. --Jola 03:33, 7 June 2007 (MDT)