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-   -   How model radiation of both solid wall and fluid£¿ (http://www.cfd-online.com/Forums/fluent/28380-how-model-radiation-both-solid-wall-fluid.html)

Harry Qiu March 29, 2001 08:52

How model radiation of both solid wall and fluid£¿
 
Hi£¬Mr. or Mrs.:

I'm modeling laminar premixed gasous combustion.

There are two zones in my geometry model, solid and fluid. The fluid zone is surrouded by the solid zone. the fluid is flue gas, and solid is ceramic(a type of non-penetratable material).

I want to model the radiatin of both ceramic wall and flame(flue gas).

After I define DO(discrete ordinat) model, I meet two difficulties (1)I don't know how to define absorption coefficient for solid(ceramic). As we all know, FLUENT set solid absorption coefficient as zero by default. Can I keep this default value "zero" as non-penetratable solid absortion coefficient? (2)When I define Boundary condition, I have to set solid zone "Participate in radiation", otherwise wall radiation will not be calculated when iteration is started. Will radiation in the interior of the solid zone be computed as in the flue gas since I set solid absorption coefficient as zero and specify solid zone "Participate in radiation"?

looking forward to your answer! Tank you for your help. Sincerely yours, Harry Qiu.

Ashutosh March 29, 2001 11:41

Re: How model radiation of both solid wall and flu
 
2) In solids if not transparent/semitransparent, you can set no participation in radiation. Solid it calculates using conduction and gets the surface temperature. You need to specify the emissivity of the wall towards fluid. There are two walls coupled (wall and wall-shadow see the fluid zone come which side and apply the emissivity of the surface). 1) For first one you need data, otherwise you can start with default value. Enjoy!!! Ashutosh

rajatca February 4, 2013 00:04

hi
 
Could you provide method to make dynamic mesh for moving box inside fluid? the moving box also needs to be thermal propery oriented. thanks,


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