Defining a non-granular phase

Tom

Hi,

I am trying to use the Eulerian Model (Fluent 6.1.22). I am trying to model a three phase system. The primary phase is caustic soda, the secondary phase is a granular particle and I would like the third phase to be water. My question is, how define this third phase as a liquid? When selecting the phase I am asked to input a diameter! I am assuming this is for something like an air bubbles, however, I would just like two liquid phases that will end up mixing together.

Any suggestion please.

Tom