DEM Pressure-Outflow BC

MFiX How to
1

The particles are supposed to escape through the ends of the 18 pipes. I have two seperate STLs, for the Walls and for the 18 Outlet-Circles in XY plane at the end of the pipes. As you can see they are in the middle of the domain not protruding out of it.
How do I properly prescribe Pressure outflow BC for it?
1)I have tried making a Region with stl of outlets checked and Filter facets based on normals, vector Z(1.0) include , invert (shows 9000 selected facets). The Pressure Outflow condition doesnt work.
2) I have tried making a plane in region in XY plane exactly at the outlets level without checking STL, it says missing fluid and wall cells.

How do I prescribe Pressure_outflow condition on the outlets without changing the geometry.
(notice that the cutting plane for the outlets also passes through the walls STL.

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2

My first recommendation is to first try with a much simpler model so you can gain experience. You said you don’t want to change the geometry, but is there a reason why you cannot extend the pipes all the way to below z_min? It is unlikely that they are physically cut-off at that plane. Would some of them intersect the large bent pipe?

If you cannot extend them, create a small rectangular block, that intersect the tubes, say one cell above your XY plane, assign a NSW BC to then. Then create a Pressure outlet along the top plane of each box.

Again, my suggestion is to try with a simpler model, say one tube so you see how it works.