Particles leaving system through outlet

MFiX
#1

I have a model of a hopper feeding grains into a box. The box is currently closed on all sides allowing a pile to form.
However now I want to put an outlet on one side of the box, so the particles drop into the box, form a pile, and some leave when the pile gets too large.

I have defined the region where I want the outlet to go, however I am unsure what the boundary condition should be for this. I do not want the particles to just roll out the box, but form a pile and only leave if pushed out. Could anybody help with this?

#2

If you want particles to leave the domain, then it must be a pressure outlet BC. You may want to post a sketch of the geometry and BC locations.

I am assuming this is DEM. Is it a granular flow or coupled (gas+solids) flow?
Are you using an STL file?

#3

Yes it is a DEM model of pure granular flow. I have attached the mfix file for this project.

rice_experiment.mfx (24.3 KB)

#4

Couple of issues:

  1. Your box is made of overlapping walls. Your geometry should only represent the internal surface of the box.
  2. The box needs to be connected to the hopper.

This means you get a mesh that is not usable, even for a granular flow. You need to fix the above and probably refine the grid spacing to get a decent mesh.

I did not see where your want to put the outlet from your project file (the “Outlet” region is not a plane and is not used as a BC).

#5

Something like this:

rice_experiment.mfx (14.6 KB)

rice_experiment.stl (248.7 KB)

1 Like
#6

Ok I understand, thank you