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-   -   Meaning of diffuse fraction,emissivity,absorption. (http://www.cfd-online.com/Forums/fluent/43813-meaning-diffuse-fraction-emissivity-absorption.html)

Ferdinando February 19, 2007 12:24

Meaning of diffuse fraction,emissivity,absorption.
 
Hi all, i'm working with DO radiation in Fluent. I want to know better the meaning of "diffuse fraction","internal emissivity","absorption". If i have a UV lamp defined as wall that emitted radiation 500 W/m^2, how can i define a near wall as a mirror? which parameters i must set? i want a specular reflection, not absorption,not trasmissivity. Please help me. Thanks in advance.

zhang.limin August 16, 2009 13:00

diffuse reflectivity specular reflectivity absorptivity
 
diffuse reflectivity = diffuse fraction(1-internal emissivity)
specular reflectivity = 1- diffuse fraction
absorptivity= diffuse fraction* internal emissivity


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