Hello everyone,
I have a model of porous media (with local thermal non-equilibrium) attached to a solid domain. I am considering porous media as a participating medium using P1 approximation. But I have a problem with energy balance in this model. I have attached now a very simple model here showing exactly the problem:
I have made two geometries:
Geom (A): I use opaque for the boundary between the porous media (with radiation participating media formulation) with the solid.
Geom (B): I'm not using opaque boundary.
After solving, I expect: Q_ltne = dU_solid (Eq. 1)
Q_ltne = the source energy term introduced by LTNE multiphysics node. dU_solid = total internal energy of the solid from initial to the end.
I mean for each of the geometries of A and B:
global evaluation 1 = global evaluation 2 global evaluation 3 = global evaluation 4
For Geom (A) this energy balance is Ok. But for Geom (B) the equality in (Eq. 1) doesn't hold anymore.
So basically I don't understand how comsol is treating this internal boundary between solid and participating media when opaque is used and why I have this energy unbalance!
I will be thankful if anyone can help me with this.
Ehsan