Species transport through porous zone
I am modelling a storage building in Fluent in which air with a certain CO2 mass fraction enters the building via an underground channel, then the air goes up through a porous zone (pile of produce) into the headspace and out of the building.
I am using a transient 2D model. I defined a CO2 mass fraction as the inlet boundary condition for CO2. I used the default wall boundary conditions. I also defined a CO2 mass source in the solid part of the porous zone. I patched a certain (constant) CO2 mass fraction in all zones of the geometry before solving.
However, there seems to be no transport of CO2 over the boundaries of the porous zone. The CO2 mass fraction is higher in the porous zone due to the source term, but this CO2 seems to be trapped in this porous zone and doesn't get transported into the headspace. In the headspace the CO2 mass fraction stays the same as the patched value.
Can anyone help me with this? What am I doing wrong?
Thanks in advance for your time!