Double Boundary
 

Can I in CFX create a boundary that has double settings? For a multiphase application I would like to have the continuous air phase to treat a specific surface as wall, but for the dispersed solid particles the surface should be an outlet. Can it be done?

Re: Double Boundary
 

Turn off the particles as they strike that particular wall?

Re: Double Boundary
 

It's an Euler-Euler approach. Two "fluids" and no particles.

Re: Double Boundary
 

Hi Dr Flow Squad!

U can try the following suggestion.

In Boundary details of an outlet define Degassing Condition in the option of Mass and Momentum,So that it will allow only dispersed phase to go out and it will restrict continuous phase to leave.

Hope it will work.

Sameer

Re: Double Boundary
 

Degassing conditon. Doesn't it work the other way around? Letting only the continuous phase to leave?

Re: Double Boundary
 

"degassing" boundary condition. Commonly used for chem reactor studies.

Re: Double Boundary
 

No, the degassing condition will allow the dispersed phase to leave. However, it is only applicable to "degassing", i.e. bubbles rising and leaving the top. I don't recall the details but it has something to do with the hydrostatic pressure.

What is it you are trying to model? There may be another approach.

Regards, Robin

Re: Double Boundary
 

I'm simply modelling a good old fashion cyclone. the loading is rather high, and I also want to determine the separation efficiency due to loading so I'm using a Euler-Euler approach instead of particles. But I want all my gas to exit at the top of the cyclone, whereas "particles" that touch the bottom surface should be collected.

Re: Double Boundary
 

What physically prevents gas from exiting the bottom?

Re: Double Boundary
 

a "snail". -