You can test if the bc.po_no_par_out flag is working by setting up the simple pseudo-1D problem:
- domain is periodic in x and z directions
- pressure inflow at y-high and pressure outflow at y-low
- gravity acting in the negative y direction
- initialize the domain with a few particles and let them settle under gravity
If the particles all ‘fall out’ then the flag is not working as expected and we’ll need to investigate.
You can test the setup in general by switching the pressure outflow at y-low with a mass inflow with zero-fluid velocity. This will ‘fake’ a wall along the bottom of the domain extent the same way the flag should impose a wall.