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Old   September 7, 2007, 09:32
Default Radiation modelling
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Hi all,

Is there any way I can define a wall which can absorb the incoming radiation but no emission or reflection takes place? I want to model a radiation problem to calculate radiation energy transfer between hot and cold plates and also between hot plate and the outside environment. Right now I have two solid bodies immersed in a fluid domain and a part of radiation emitted by these bodies is reflected back by the fluid domain walls. I want to assign properties to fluid domain walls in a way they will not emit or reflect any radiation.

I have tried emissivity as '0' but in that case there was no emission but all the incident radiation reflected back. I also tried emissivity '1' and room temperature boundary on fluid domain wall but still my results are not looking good.

I appreciate your help.


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Old   September 7, 2007, 10:02
Default Re: Radiation modelling
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Dear Deeps,

I would like to know what you are trying to model. It defies my understanding of radiative heat transfer. By Kirchoff law, absorptivity = emissivity ; therefore, if it absorbs it must emit.

Do you want to know exactly how much radiative energy is reaching the cold plate? Take a look at the Wall Irradiation Flux variable in CFX-Post. Similar for the hot plate.

Is it a participating or a transparent material? For the transparent case, you can setup separate cases where you study the Hot->Cold plate interaction alone.. For example, set the all boundaries (except hot plate) to 0[K] and e=1 and you will see where the energy leaving the hot plate is going. Repeat similar setup for the cold plate, and you can see similar effect. When all the plates are active, the solution is the combination of the separate effects.

Hope this helps,


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Old   September 7, 2007, 10:12
Default Re: Radiation modelling
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Thanks for your response.

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