kEpsilonPhitF is a kEpsilon-based model which originated from (Durbin, 1995)’s v2-f methodology. However, the majority of v2-f model variants proved to be numerically stiff for segregated solution algorithms due to the coupled formulations of v2 and f fields, particularly on wall boundaries.
The v2-f variant (i.e. OpenFOAM’s v2f model) due to (Lien and Kalitzin, 2001) reformulated the original v2-f model to enable segregated computations; however, a number of shortcomings regarding the model fidelity were reported in the literature.
To overcome the shortcomings of the v2-f methodology, the v2-f approach was re-evaluated by (Laurence et al., 2005) by transforming v2 scale into its equivalent non-dimensional form, i.e. phit, to reduce the numerical stiffness. This variant, i.e. kEpsilonPhitF, is believed to provide numerical robustness, and insensitivity to grid anomalies while retaining the theoretical model fidelity of the original v2-f model.
Accordingly the v2f RANS model is deprecated in favour of the variant kEpsilonPhitF model.