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Flux variable is not converged - Heat transfer

Posted 21.10.2013, 04:18 GMT-4 4 Replies

Anderson Singulani
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Hi,

I am performing a Heat Transfer in Solids simulation. It runs "fine" and the results seems reasonable but I get a warning in the end that reads: Flux variable is not converged. Does anybody knows what this mean?

Thanks,
Anderson.
4 Replies Last Post 10.12.2014, 05:11 GMT-5
COMSOL Moderator

Hello Anderson Singulani

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Judith Hoerstmann
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Posted: 10 years ago 09.12.2014, 10:30 GMT-5
Hi!

I get the same warning during a simulation of heat transfer in fluids and solids. Did you find out what it means?

Thanks,

Judith
Hi! I get the same warning during a simulation of heat transfer in fluids and solids. Did you find out what it means? Thanks, Judith
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 10 years ago 10.12.2014, 02:09 GMT-5
Hi

my best guess is that the coherence between the different fluxes calculated over your boundaries is not precise enough for a given criteria, could be a too course mesh or some singularity points.

Have you tried to do some local mesh refinements ?

--
Good luck
Ivar
Hi my best guess is that the coherence between the different fluxes calculated over your boundaries is not precise enough for a given criteria, could be a too course mesh or some singularity points. Have you tried to do some local mesh refinements ? -- Good luck Ivar
Anderson Singulani
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Posted: 10 years ago 10.12.2014, 02:40 GMT-5
Hi Judith!

To be honest, I still don't know precisely what Comsol try to inform us with this message, but I had the same interpretation as Ivar. A finer mesh didn't help me back there, but I simplified a bit the geometry and after that the warning disappeared.

Kind regards,
Anderson.
Hi Judith! To be honest, I still don't know precisely what Comsol try to inform us with this message, but I had the same interpretation as Ivar. A finer mesh didn't help me back there, but I simplified a bit the geometry and after that the warning disappeared. Kind regards, Anderson.
Henrik Sönnerlind COMSOL Employee

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Posted: 10 years ago 10.12.2014, 05:11 GMT-5
Hi,

This message appears when the computation of 'accurate boundary fluxes' fails for some reason. It does not mean that the solution is bad in any other respect, or that flux conservation is bad. It only means that the postprocessing variables for the boundary are not useful.

To learn more about the boundary flux variables, please refer to 'Computing Accurate Fluxes', 'Boundary Heat Fluxes', and 'Internal Boundary Heat Fluxes' in the documentation.

Regards,
Henrik
Hi, This message appears when the computation of 'accurate boundary fluxes' fails for some reason. It does not mean that the solution is bad in any other respect, or that flux conservation is bad. It only means that the postprocessing variables for the boundary are not useful. To learn more about the boundary flux variables, please refer to 'Computing Accurate Fluxes', 'Boundary Heat Fluxes', and 'Internal Boundary Heat Fluxes' in the documentation. Regards, Henrik

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