Why won't the fluid flow past pressure outlet?
 

Hello there,
I am currently trying to model the injection of CO2 into a saline aquifer where the injection pipe has a fracture, so that I can evaluate the migration of the leaked CO2. My model is basically a pipe, however I have added a very small protrusion which I can then assign boundary conditions to in order to model the fracture extends into a layer of porous sandstone. I have assigned BC's of velocity-inlet to the inlet of the injection pipe and then a pressure outlet to both the outlet of the pipe and the fracture. On running the simulation and looking at the results the actual flow through the pipe and around the fracture seem ok, but the flow doesn't continue through the fracture pressure outlet into the sandstone zone. Does anybody know how I can resolve this?
Thank-you :)

If you want flow to continue from the pipe into the sandstone, you'll need an interior boundary condition, such as an interface (See Fluent User's Guide section 5.4). The outer edges of the sandstone will have pressure outlets or some other kind of exterior boundary condition instead.