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-   -   thermal resistance in cht problems (https://www.cfd-online.com/Forums/openfoam/124695-thermal-resistance-cht-problems.html)

 pangelo October 11, 2013 01:43

thermal resistance in cht problems

Hi everybody,
I am at my first experience with openfoam and I am interested in simulating a steady-state cht problem.

So far I was able to run a simple case by using the chtMultiRegionSimpleFoam solver. In order to create the interface between the different regions, I have used the turbulentTemperatureCoupledBaffleMixed.
This boundary works fine but I did not find any method to set the thermal resistance between two solid parts.

Please, can you suggest me a strategy in order to solve this problem?

 Ahmed Khattab October 11, 2013 09:48

welcome bangelo,

please could you explain what do you mean by thermal resistance between solid regions. thermal conductivity is already defined for every solid region.

 mturcios777 October 11, 2013 12:03

He means the inverse of the thermal contact conductance:
http://en.wikipedia.org/wiki/Thermal_contact_conductance

This should be handled with a boundary conditions, but I don't know if Foam has such conditions (haven't dug deep enough myself).

 Ahmed Khattab October 12, 2013 03:12

hi marco,

i think he don't need to input such resistance as he will entering thermal conbuctivity. then openfoam will deal with it or convert it to resistance.

am l right?

 pangelo October 14, 2013 08:01

Quote:
 Originally Posted by mturcios777 (Post 456397) He means the inverse of the thermal contact conductance: http://en.wikipedia.org/wiki/Thermal_contact_conductance
Hi Marco, this is exactly what I mean.

Quote:
 Originally Posted by rebel ahmed (Post 456486) i think he don't need to input such resistance as he will entering thermal conbuctivity. then openfoam will deal with it or convert it to resistance.
Hi Ahmed, what you say would be right if you really simulate the contact region between the two parts. Anyway, as the contact region is very thin (we are speaking about some microns), its mesh would be very demanding and for this reason one prefers to work with its thermal resistance (thickness/k).

The link Marco posted shows very well what I mean.

 Ahmed Khattab October 14, 2013 11:57

Dear Pangelo,

this information is really new for me, thanks for your information. i think there is a case in openFoam.2.2.0 for cooling of electronic circuit, maybe you will find your target there.

thanks and good luck

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