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Natural convection

Posted Mar 28, 2017, 7:03 a.m. EDT Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD) Version 5.2, Version 5.2a 2 Replies

Meryeme BOUMAHDI
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Hi I'm beginner with comsol. I want to simulation the natural convection in the air. Heat transfer in fuid with laminar flow, It's works with short time (for 1 or 2 min) but it never give me results for more then 2 min. I have all the time this error message "Repeated error test failures. May have reached a singularity.".
Any idea why this is happening.
2 Replies Last Post Mar 31, 2017, 1:04 p.m. EDT
Mahvash Afzal
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Posted: 8 years ago Mar 31, 2017, 12:58 a.m. EDT
Meryeme,

You can try refining your mesh or it could be because of incorrect boundary conditions.

Best,
Mahvash
Meryeme, You can try refining your mesh or it could be because of incorrect boundary conditions. Best, Mahvash
Jim Freels mechanical side of nuclear engineering, multiphysics analysis, COMSOL specialist
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Posted: 8 years ago Mar 31, 2017, 1:04 p.m. EDT
Start with a very small "load", which in this case, probably the temperature difference that drives the simulation. Make sure you have gravity enabled to be included as body-force term in the momentum equation. As the temperature difference gets larger, eventually the solution should get unstable. See discussion on Rayleigh number (en.wikipedia.org/wiki/Rayleigh_number).
Start with a very small "load", which in this case, probably the temperature difference that drives the simulation. Make sure you have gravity enabled to be included as body-force term in the momentum equation. As the temperature difference gets larger, eventually the solution should get unstable. See discussion on Rayleigh number (https://en.wikipedia.org/wiki/Rayleigh_number).

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