Heat Flux and Radiation at same boundary

MarioArias · March 11, 2015, 15:20

Hello,

I am trying to model a heat flux boundary condition on a surface, and would like to allow it to radiate into a vacuum. Is P-1 the correct radiation module?And if so, Do i just change the emissivity to a gray body where i want it to radiate, and 0 to any i want shielded in the boundary conditions?

Thanks,
Mario Arias

vasava · March 12, 2015, 09:56

I did not understand what you mean by 'shielded'. Anyways with P1-model you will only have emissivity (for radiations) in the boundary setup. 'External Emissivity' for walls and 'Internal emissivity' for walls shared by the interfaces.

The choice of model would depend upon optical thickness. P-1 is good for optical thickness larger than 1. DO and DTRM do not have any such limitations and are more widely applicable. Also with DO you will have more choices over boundary conditions as you can also have semi-transparent material (e.g. glass) in the simulation.

P.S: I too have started learning about radiation since last week. My answer is based on my very brief experience with simulating radiations with fluent.

MarioArias · March 13, 2015, 05:47

All I have is a square microchannel heat exchanger. I am set a heat flux boundary condition on a single wall of that heat exchanger, and I would like to let it radiate to a vacuum.

March 11, 2015, 15:20	Heat Flux and Radiation at same boundary	#1
MarioArias New Member Mario Arias Join Date: Mar 2015 Posts: 6 Rep Power: 11	Hello, I am trying to model a heat flux boundary condition on a surface, and would like to allow it to radiate into a vacuum. Is P-1 the correct radiation module?And if so, Do i just change the emissivity to a gray body where i want it to radiate, and 0 to any i want shielded in the boundary conditions? Thanks, Mario Arias

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March 12, 2015, 09:56		#2
vasava Senior Member Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 732 Rep Power: 23	I did not understand what you mean by 'shielded'. Anyways with P1-model you will only have emissivity (for radiations) in the boundary setup. 'External Emissivity' for walls and 'Internal emissivity' for walls shared by the interfaces. The choice of model would depend upon optical thickness. P-1 is good for optical thickness larger than 1. DO and DTRM do not have any such limitations and are more widely applicable. Also with DO you will have more choices over boundary conditions as you can also have semi-transparent material (e.g. glass) in the simulation. P.S: I too have started learning about radiation since last week. My answer is based on my very brief experience with simulating radiations with fluent.

March 13, 2015, 05:47		#3
MarioArias New Member Mario Arias Join Date: Mar 2015 Posts: 6 Rep Power: 11	All I have is a square microchannel heat exchanger. I am set a heat flux boundary condition on a single wall of that heat exchanger, and I would like to let it radiate to a vacuum.