On the choice of a phase interchange strategy for a multiscale DEM-VOF Method

In this work a novel Multiscale DEM-VOF method is adopted to study three phase flows. It consists in solving the fluid
momentum, mass conservation and the phase advection at a different scale with respect to the fluid-particle coupling problem.
This allows the VOF scheme to resolve smaller fluid structures than a classic DEM-VOF method, and opens the possibility of
adopting different volume interchange techniques. Two different volume interchange techniques are here described and compared
with reference to high and low particle concentration scenarios. Considerations about the respective computational costs are also
proposed.