12.13.5 Differential Viscosity Modification

The RNG turbulence model in ANSYS FLUENT has an option of using a differential formula for the effective viscosity $\mu_{\rm eff}$ ( this equation in the separate Theory Guide) to account for the low-Reynolds-number effects. To enable this option, the Differential Viscosity Model option under RNG Options in the Viscous Model dialog box needs to be enabled.

This option appears when you have activated the RNG $k$- $\epsilon$ model.