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Interface Model:None or zero thermal conductance?

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Old   October 10, 2010, 10:16
Default Interface Model:None or zero thermal conductance?
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Dear all,
In defining domain interfaces in CFX there are 3 options for interface model: None,Thermal conductance and Thin Material.
what is the difference between choosing none or a zero thermal conductance?
I have solved the same problem with these two options and I got different results.
Thanks
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Old   October 11, 2010, 04:04
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anton.gardi
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I think you should have a look in the help . the physics is different in every case. in case you have a solid immersed in a fluid you should check also what the conjugate heat transfer is ..
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Old   October 11, 2010, 14:41
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I read the documentation but there is no description for the none option.
The two others do the same job in different ways.

"Heat Transfer


Determines whether or not heat transfer models are applied between the sides of the interface.
The options are:
  • Conservative Interface Flux
    This option enables you to define the Thermal Contact Resistance or Thin Material, which are two ways of defining the same characteristics. That is, if you do not know the contact resistance, you can define the thin material and its thickness and have the solver derive the resistance"
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Old   October 11, 2010, 18:09
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Glenn Horrocks
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None means no interface material, and heat is transferred across the interface with no loss or resistance. The other options add thermal resistance, they just calculate the thermal resistance different ways.
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Old   October 12, 2010, 01:43
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Dear ghorroks,
If so None and a zero thermal resistance must give the same result, I have tried this and the results were different!
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Old   October 12, 2010, 18:18
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Glenn Horrocks
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I have not used these options so do not know in detail. But I would have assumed zero thermal resistance then should be the same as the none option. If you have a case which shows it is not the same then talk to CFX Support as you may have found a bug.
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Old   October 12, 2010, 22:15
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Quote:
Originally Posted by mak86 View Post
Dear ghorroks,
If so None and a zero thermal resistance must give the same result, I have tried this and the results were different!
How different? Provide plots.
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