Nikhil Narale
Ansys Employee

Here are some excerpts regarding Explicit Volume Fraction Formulation from the Ansys Help. Hope this clears your doubts!

"Since the volume fraction at the current time step is directly calculated based on known quantities at the previous time step, the explicit formulation does not require and iterative solution of the transport equation during each time step."

"The explicit formulation is non-iterative and is time-dependent."