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Radiation in participation media and LTNE - an energy balance problem

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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



1 Reply Last Post 2018年10月10日 GMT-4 16:30

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Posted: 6 years ago 2018年10月10日 GMT-4 16:30
Updated: 6 years ago 2018年10月10日 GMT-4 16:32

Is anyone familiar with such problems? I will really appreciate the help.

Thank you

Is anyone familiar with such problems? I will really appreciate the help. Thank you

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