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Old   May 31, 2004, 09:25
Default Radiation and Symmetry
  #1
Eric
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Hi all,

Can anyone tell me if the radiation models are realiable when using symmetry?

As the radiation models are based on reflection, can fluent account for radiation that may cross the symmetry axis? For example a cylindrical furnace using symmetry along the longitudinal axis.

Thanx

Eric
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Old   May 31, 2004, 10:02
Default Re: Radiation and Symmetry
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Rami
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Eric,

I cannot comment about fluent treatment of symmetry for radiation as I have never used it. However, any radiation solver implemnting specular reflection may be used to simulate symmetry. Symmetry surface is merely a perfect specular reflector. For the axis of a cylinder, the approach I use (FVM) naturally treats this zero area surface (any finite flux results in zero power for zero surface area).

I hope this helps,

Rami
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Old   June 3, 2004, 06:55
Default Re: Radiation and Symmetry
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nuray
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Radiation models solve intensity(I) for each grid point and direction. if possible, print the intermediate intensity values in the domain for a sweep. If symmetrical boundary condition is implenmeted correctly, at the symmetry axis incoming intensity should be equal to out going intensity with a different sign. Here is the bc

I_m = I_mī

where m : incoming direction

mī: outgoing direction

There are simple test cases available in the radiation heat transfer books for cylindrical media.

Quickest way: Radiation model provides source term to energy equation. if you donīt see any non-symmetric temperature profile along z axis it means that it works.

Nuray
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Old   June 3, 2004, 07:30
Default Thanks nuray and Rami
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Eric
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