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-   -   Interface Model:None or zero thermal conductance? (http://www.cfd-online.com/Forums/cfx/80888-interface-model-none-zero-thermal-conductance.html)

mak86 October 10, 2010 10:16

Interface Model:None or zero thermal conductance?
 
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

gardian October 11, 2010 04:04

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 ..

mak86 October 11, 2010 14:41

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"

ghorrocks October 11, 2010 18:09

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.

mak86 October 12, 2010 01:43

Dear ghorroks,
If so None and a zero thermal resistance must give the same result, I have tried this and the results were different!

ghorrocks October 12, 2010 18:18

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.

michael_owen October 12, 2010 22:15

Quote:

Originally Posted by mak86 (Post 278749)
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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