Inlet and Outlet in the same boundary
 

Hello.

I've been working with finite elements simulation for a while now, but I'm new to CFX.

Recently I've been trying to simulate the following process:

Geometry: Cylindrical column
Fluids: Hot air and solid
Situation: The column has a lateral opening where hot air is blown, an open top from where solid is introduced and hot gas is collected and an open bottom from where solid is collected.
The objective is to react the solid with the hot air and collect the resulting gas from the top and the reacted solids from the bottom.

My problem lies with some of the boundary conditions for each of these openings.

1 - For the lateral opening, no problem, I just have to set it as an inlet and set the normal speed of the air injection and the volume fraction of air equal to 1 and the solid's equal to zero.

2 - For the bottom opening, no problem also, as I only have to set it as an outlet and set the mass outflow rate for the solids.

3 - But for the top opening, I don't know what to do. I have to conditions to impose: the solid's inflow rate and the gases' outflow rate. How can I do this? Is there a way to set this boundary as an inlet for the gas and a outlet for the solids???

Thanks very much for your help.

Have a nice day!

Can you post your geometry?

http://s2.postimage.org/5629ao1x7/tny.png
hosting images
Here it is.
The lateral inlet is clear in the picture.
The bottom outlet is located right under the lateral inlet.
And the problematic boundary is the one on the top. In which I wanna apply a outlet boundary condition for the gas phase and a inlet boundary condition for the solids.