how to set the parameters in simulating the natural convection

hook · January 14, 2010, 05:20

Dear Mrs. and Mr.,
I'm simulating a heat transfer problem coupled convection and radiation heat transfer to ambient air. I choose the DO model for the radiation process. The solid wall is aluminum and the emissivity is 0.2.
But I'm faced with the embarrassing situation that I don't know where to decide the emissivity coz there exist two choices, namely the internal emissivity and the external emissivity. What's the differences between the two?
What's more, in my simulation model, the faces contacting the solid domain and the air domain are COUPLED, and there is no external emissivity. I notice that the external emissivity only exists under the MIXED panel. The other panels including heat flux, convection, radiation are not including the external emissivity.
What shoud I do in my situation? What the devil differences are between the two emissivities?
Many thanks for any information you provide.
Hook

hook · January 17, 2010, 02:33

Why not help me? I'm very anxious.

January 14, 2010, 05:20	how to set the parameters in simulating the natural convection	#1
hook New Member Join Date: Jan 2010 Posts: 7 Rep Power: 16	Dear Mrs. and Mr., I'm simulating a heat transfer problem coupled convection and radiation heat transfer to ambient air. I choose the DO model for the radiation process. The solid wall is aluminum and the emissivity is 0.2. But I'm faced with the embarrassing situation that I don't know where to decide the emissivity coz there exist two choices, namely the internal emissivity and the external emissivity. What's the differences between the two? What's more, in my simulation model, the faces contacting the solid domain and the air domain are COUPLED, and there is no external emissivity. I notice that the external emissivity only exists under the MIXED panel. The other panels including heat flux, convection, radiation are not including the external emissivity. What shoud I do in my situation? What the devil differences are between the two emissivities? Many thanks for any information you provide. Hook

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January 17, 2010, 02:33		#2
hook New Member Join Date: Jan 2010 Posts: 7 Rep Power: 16	Why not help me? I'm very anxious.