4.4 Standard, RNG, and Realizable $k$- $\epsilon$ Models

This section describes the theory behind the Standard, RNG, and Realizable $k$- $\epsilon$ models. For details about using the models in ANSYS FLUENT, see this chapter and this section in the separate User's Guide.

This section presents the standard, RNG, and realizable $k$- $\epsilon$ models. All three models have similar forms, with transport equations for $k$ and $\epsilon$. The major differences in the models are as follows:

• the method of calculating turbulent viscosity

• the turbulent Prandtl numbers governing the turbulent diffusion of $k$ and $\epsilon$

• the generation and destruction terms in the $\epsilon$ equation

The transport equations, the methods of calculating turbulent viscosity, and model constants are presented separately for each model. The features that are essentially common to all models follow, including turbulent generation due to shear buoyancy, accounting for the effects of compressibility, and modeling heat and mass transfer.