abt near wall turbulence wall functions

amv

Hi to all the "turbulent" experts !

I am trying to develope a code which can solve turbulent flow, attached/separated ! e.g. turbulence flow over a backward facing step. The turbulence model i am using is k-epsilon. I found that, in such cases, where there are separation region/s, the formulation of wall functions plays a vital role in the predictions of turbulent kinetic energy and dissipation rate.

what is the best near wall treatment for implementing k-epsilon model, amongst Amano, Rodi and Chiang/Launder ?