connecting a small volume to the one containing it

Djalil

Hi, I want to follow an aerosol in a room (brick) containing a tubular reactor (small cylinder), which provides the energy for the movement. However, the particles produced at the entrance of the cylinder (velocity inlet)only move inside of it and dont get out through the outlet surface (pressure outlet) into the room. I suppose there is a problem of "connection" between the 2 volumes and I still dont get it fixed :-[ I hope someone can help!

kind regards!