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July 16, 2004, 09:48 |
Emissivity for boundary condition
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#1 |
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I am modeling the heat flow in a concrete floor heated with imbedded hot water pipes. For the top surface boundary condition I am using the mixed thermal conditions, where I can input the external emissivity and temperature for the radiative heat transfer. I can't find any place (such as "define materials") to input the emissivity of the concrete surface though. Even if I select radiation under "define models" I can't find any place to provide the surface emissivity. How does FLUENT calculate this? Does it assume an emissivity of the boundary of 1? Thanks for any information you can provide.
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July 16, 2004, 12:13 |
Re: Emissivity for boundary condition
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#2 |
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What Radiation model are you using?
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July 16, 2004, 12:59 |
Re: Emissivity for boundary condition
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#3 |
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I am not using a radiation model. I am just using the energy model but, I can still use a mixed boundary condition that incorporates both convection and radiation. It is the radiation part that I don't know how FLUENT calculates.
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July 25, 2004, 04:48 |
Re: Emissivity for boundary condition
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#4 |
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Dear ereiss ,you should take a global convection coeficient which includes conv+radiation
h=24.1*e-4*epsilon*pow(T,1.61) epsilon :emissivity ,T temperature and you write a UDF for this...... |
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August 10, 2012, 01:27 |
External radiation
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#5 | |
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n7310889
Join Date: Aug 2012
Posts: 26
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Quote:
Could you please write the equation a bit clearly? And is it possible for you to give a reference for that, so that I can make some study. Another request is, I am modeling a conjugate heat transfer problem (liquid coolant flow through a tube), in which I have to give three boundary conditions on the outer surface of the tube: (non-uniform) functional heat flux as heat input, radiation loss and convection loss. But I don't understand how can I ensure all of these 3 at a time. Could you please suggest me? I'll be happy if you may text me in my email. Regards n7310889 (murad99me@yahoo.com) |
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