Semipermeable surface in DES

MFiX How to
#1

Continuing the discussion from How to simulate mesh filter:

I’ve just tried this in a DES simulation but I get:

Error 1000: DES simulations do not support the
specified IS TYPE:
IS: 1
IS_TYPE=SEMIPERMEABLE

Is there a way to do filter simulations in DES mode? I’ve based my model on the fluidized bed superdem example, which doesn’t allow particles back through the inlet if you set the gas velocity low. But I can’t find a reliable way of preventing particles leaving at an outlet. I’ve tried using a mass outflow with the fluid matched to the inlet and a solids velocity or mass flow rate of 0, but 90+% of the particles
just pass through anyway.
I also though of using a 2nd pressure inlet but with a reduced pressure so the flow would be reversed, but this is trapped in check_bc_dem.f .

Is there any other way to stop solids leaving through an outlet?
Thanks,
Alan

#2

Try setting BC_PO_APPLY_TO_DES(#BC) = .FALSE.

You can do this through the Advanced pane in the GUI. Click “+” to add a keyword, add this one, and set the index to the index of the BC in question (these are listed in the table at the top of the BC pane)

#3

Thanks Charles, that appears to be working fine.