https://forum.ansys.com/discussion/comment/109160#Comment_109160The VOF itself is not valid for my problem, and this is the reason why I include a diffusion term.https://forum.ansys.com/discussion/comment/109212#Comment_109212

I Understand this. But I also understand that you want to compare the UDS with VOF for validation. That is why I suggested comparing with explicit formulation ... The solver solves your UDS explicitly at the end of the iterations after solving all the standard equations. So, it does make more sense to me that you compare with explicit formulation ... and would make more sense if you compare with Non-Iterative solutionn