Learning Forum

[tanmoy]

Now I have a geometry made of carbon inside Vaccum chamber . Now emissivity of carbon is around 0.8. Now in fluent there are two options "internal" and "external" emissivity. Now what will be internal emissivity here? will it be 0.8? or 0.2?  Now there is no other source which will cause radiation but one part of my geometry will contribute to increse temperature in other part. In that case what will be my external emissivity?

thanks in advance!

[Rob]

What does the manual say?

[tanmoy]

It says...

" external emissivity = emissivity of the external wall surface defined by you"

now" external wall " of what?? outer wall of geometry or inside wall of the chamber( inside which my geometry is placed)?

for internal emissivity, it is written "sets the internal emissivity of the wall"

now what does that "internal" word mean?? an open surface will emit outside. does this internal means amount of heat that surface will allow to enter the volume??

 

[Rob]

And which model/panel are you looking under?  External typically means it's leaving the model (ie an outer wall) and internal typically means into the fluid/domain.