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Old   February 14, 2009, 07:19
Default Radiation with adiabatic wall
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Hi experts!! I have a simple box with inlet, outlet and one windows,it's 2d, there is radiation, I have a radiation source and the the thermal radiation model is Monte Carlo. my domain is air. I would set adiabatic wall (the wall is only the line of the box, it hasn't thickness), but the problem is that if I set adiabatic wall, the temperature near the wall decreases also of 100 degree. the tutorial with radiation has only a fixed temperature wall, not adiabatic... (with a fixed temperature my model works, but it isn't as my physical case...). How could I resolve it? thanks
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Old   June 20, 2014, 13:43
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I have the same problem. Can anyone guide me what to do with that? When I use adiabatic boundary condition (thermal energy) on the wall , I have non zero heat flux on the wall. What is the reason?
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Old   June 23, 2014, 10:47
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From the documentation (heat transfer boundary condition section):

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The heat flux across the wall boundary is zero (that is, insulated). When radiation is included, the total heat flux is zero:
If a wall is adiabatic, and the net radiative heat flux is non-zero, this energy must be transferred somewhere by other mechanism such conduction, advection, phase change, etc. If you only have conduction/advection, you will see a non-zero convective or conductive wall heat flux at such boundary.

Hope the above helps,
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Old   June 23, 2014, 12:00
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Dear Opaque,
Thank you very much for your response.
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Old   June 27, 2014, 02:33
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you can change from adiabatic to thin wall (with defined outside temperature and thermal conductivity if you know this values from your BCs).
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Old   June 27, 2014, 12:55
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Thank you Martin_Sz. It is a good idea.
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