Multiphase species transport
 

Hello,

I'm having a problem with Fluent regarding mass transfer between phases of species.

Just for testing purposes, we've created a simple geometry consisting in a 2D rectangle (5 mm wide and 10 mm height). We divided the rectangle in half, so that each of the half's would contain one phase. So in total we have 2 phases. The domain is closed, there is not inlets and no outlets, it's an isolated system where we want a specie to go from phase-2 to phase-1.

In top part of the rectangle, we have phase 2:
- 50% oil (same properties of water) and 50% tracer (same properties of water)

In the bottom parte, we have phase 1:
- 100% water and 0% tracer (same properties of water)

Initially we assumed an equilibrium ratio of 1, so I would expect that 50% of the tracer from phase 2 would be transferred to phase 1.

I'm currently using an Eulerian model (Multi-VOF), and I am assuming a constant mass transfer coefficient of 1000 (it's not realistic, I know).

The transfer mechanism is from phase-2 to phase-1 of tracer. The problem is that everytime I try to simulate this, nothing appears to happen. Nothing other than some residual amount of tracer in phase-1 (like 1e-10 or something, which I don't really attribute to the physical model, but maybe numerical problem). Has anyone tried something similar?

This is just a preliminary test, because what I really want to simulate is a pure diffusional mas transfer in the interphase, which I believe, I need an UDF to do so.

Thanks

PS: posted again on Multiphase subforum. Please delet this

I'm not too familiar with the VOF model, but I would think that maybe the challenge may be how you are defining the tracer, and how this is related to the volume (Vfraction-phase2 = 0.5 of oil) occupied in the secondary phase.