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-   -   Need help in setting up multiphase flow (http://www.cfd-online.com/Forums/fluent/114929-need-help-setting-up-multiphase-flow.html)

RodriguezFatz March 20, 2013 04:40

Need help in setting up multiphase flow
 
1 Attachment(s)
Dear all,

I need some help with a multiphase flow setup. It looks like this:
Attachment 20024
Some air/water mixture enters the cylinder in the middle, now water should leave at the lower outlet and air should leave at the top. In reality the water surface is controled via level sensors. Up to now I could not get a water / air - surface generated.
I already tryed several things but I am stuck now...

What I found out is that I probably need RSM turbulence model since the flow starts to rotate strongly in the tube. Only RSM and the k-w model converged for single phase flow. Air percentage can be as high as 20%, so I use the mixture model (<- is this right, or do I need to use the eularian model?).

My questions are:
1) How will I set up the two outlets? Two pressure-outlets? Both the same pressure?
2) Up to now I had both air and water incompressible. I set the gravity to -9.81. Is this enough for buoyancy effects of air bubbles in water, or do I need to play with "operating density" and stuff like that to "activate" bouancy effects?

You see, I am quite a rookie with these things...

RodriguezFatz April 2, 2013 03:47

Hi, no one who can help me?


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