Cavity radiation in thermal analysis

General Questions
1

Hello at all,
I simulate cavity radiation in a rectangular tube (3D). I have a few questions about this.

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  • Which “Sink temperature” should I use? A YouTube tutorial recommended -10K. Is this temperature valid for all cases?

  • In the same video (2D model) the edges of the cavities with cavity radiation were defined individually. Does this rule also apply to 3D models? Or can all four surfaces be assigned boundary conditions at once?

Thanks very much

2

I used this value in my tutorial since according to the ccx documentation:

Sometimes, it is useful to specify that the radiation is closed. This is done by specifying a value of the environment temperature which is negative if expressed on the absolute scale (Kelvin). Then, the viewfactors are scaled to one exactly.

They were defined individually only because of the fact that each edge had different emissivity assigned.

3

Thank you very much for your quick feedback!