Kutalmış Berçin authored Dec 21, 2019 and Andrew Heather committed Jan 03, 2020

  - 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.