Rob
Ansys Employee
To clarify, the "solid" in Fluent is something that can only move my mesh deformation. The solidification/melting model works on the fluid only and "freezes" that fluid so it doesn't move, it does not turn the frozen material into a solid.
In simulation phases and other definitions are slightly different. So oil and water would be considered as two phases even though they're both liquids. Similarly two different sized grannular particles of the same material would be set as two distinct granular phases, and they're be a fluid material type as they "flow" and move with the carrier fluid phase.