k-Epsilon RNG Model

The RNG κ-ε turbulence model isn’t significantly different from the standard model. It’s derived using a statistical technique called renormalization group theory (RNG) and differs from the standard model in the following ways:

1. The RNG model includes additional terms in the ε equation, enhancing accuracy for fast-strain flows.
2. It incorporates the effects of swirl on turbulence, thereby improving accuracy for swirling flows.
3. In the standard model, it assumes high Reynolds numbers, while RNG analytically derives equations from the effective viscosity equation, considering low Reynolds number flows. However, optimal results still require specific treatment around the walls.

Here are the transport equations for the RNG κ-ε turbulence model:

(6.8)

And

(6.9)

Not significantly different from the standard equations, but in these equations, alpha,k,epsilon represents the inverse (reciprocal) of the effective Prandtl number and effective viscosity, miu,eff.

Reference:

Caesar Wiratama. Theory and Best Practices of Computational Fluid Dynamics. PT Tensor Karya Nusantara, Yogyakarta. 2025