Questions of fluid pairs
 

Hello. I'm doing a simulation on CFX. My case is distribution box, or a kind of launder, that has one input and 3 outputs. It's isothermal and transient. I have three phases involved: water, air, and particles. The water transports the particles, and the air is above. I did my case already with water and air, and it was OK. The thing is that now, I'm not sure about the fluid details and the fluid pairs. My questions are the following:

1. For the particle phase, in fluid details-morphology, I put dispersed fluid. This is because I want to use an Eulerian-Eulerian model. If I put dispersed solid I'm I using Lagrangian method?

2. For fluid pairs, for the pair water-particles, under interphase transfer I only have the options of free surface or particle model. Does particle model mean I'm using Lagrangian particle tracking?

3. In fluid pairs, under interphase transfer, for water-air I used free surface. I'm not sure what the difference is between this and mixture model.

4. In fluid pairs, under interphase transfer, for particle-air I used free surface. I'm not sure if this is OK, because the particle phase should carried by the liquid, and I don't know what interaction should it have with the air. Is free surface OK?

Thank you very much.

Francisca

firsly I'd suggest for you to have a review on the multiphase section in cfx manual

an Eulerian-Eulerian particle transport assumes all particles have the same mean diameter and have the velocity of the transporting fluid etc etc..

for a Eulerian-Lagrangian particle tracking setup you have more options to chose from including the effect of the particle on the flow, particle size distribution and many more. this is two totally different models and to distinguish how you set them up for the Eulerian-Lagrangian particle tracking setup its the particle tracking option in the first tab of your domain settings window.

as for the rest of your questions before proceeding any further with your model I'd suggest to revisit the tutorials with the chimney with smoke, the mixing vessel and the air bubbles.