Control flow with the geometry
 

http://img8.imageshack.us/img8/5585/pictureqvk.jpg

(Black color = Wall. White color = solid particle. Blue color = liquid)

When I run the multiphase model (ex: Eulerian Multiphase Model), how can I programed the flow through the narrow hole.

If I don't program anything, the Fluent will solve this problem normally (large particle flow pass the smaller hole)---> the result isn't correct.

So I want to know how to make the Fluent know that if the diameter of particle is bigger than the width of the hole, there will be not the flow pass the hole, and the particle will flow back.

Thank you very much.