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Old   March 18, 2003, 08:17
Default Radiation CFX 5.5
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I am working on oven for backing bread. I use P1 radiation method.

I would like to look only surface-to-surface radiation without air radiation. Is this posible with CFX5.5?

What should I take for absorbtion,scattering and reflection coefficient for air.

Could somebody tell me how CFX calculate radiative emission, incident radiation and radiation intensity? Equations pleace.

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Old   March 18, 2003, 13:56
Default Re: Radiation CFX 5.5
Jeff Moder
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I am not a CFX user, but if you only want to do surface-to-surface radiation, i would recommend not using the P1 method if you want reasonable accuracy; you can probably get qualitative results for transparent media with P1, but heat flux errors could easily approach 30% or more. The P1 approximation is better suited to participating media with large absorption.

If CFX has a discrete ordinates or discrete transfer method, i would recommend using these, even if you only use a very small number of directions.
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Old   March 18, 2003, 19:34
Default Re: Radiation CFX 5.5
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I agree with Jeff's comments.

The P1 radiation model is not good for surface-to-surface radiation, but produces reasonably good results when the optical thickness >1 (we've used it with reasonable success for gas combustion problems).

For optically thin media, discrete transfer/ray trace based models are much better. These will be available in CFX-5.6 (available April ?)


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Old   March 21, 2003, 02:44
Default Re: Radiation CFX 5.5
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Could someone give me useful value for absorbtion,scattering and reflection coefficient for air.
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