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Flow simulation to improve heat sink design - Problem! No temperature gradient across fins!

Question asked by Jamshid Sadeghi on Nov 26, 2013
Latest reply on Dec 11, 2013 by Kyu-Hyung Kim

Hello all,

 

I am trying to do a study into LED heat sink design and performance in Solidworks with the Flow Simulation, but I am getting results which I think are wrong (although this is most likely to do with how I set up the study).

 

Until now I had been using an external study, selecting Conduction in solids and Gravity from the wizard menus.

 

I applied a volume heat source to the part that is the LED COB in the assembly.

 

I then made a thermal joint between the bottom of the LED COB part and the surface of the heat sink which it is sitting on.

 

Finally I selected all the exposed faces of the heat sink and set a contact resistance of ground aluminium and air.

 

When I run the study and check the results the temperature throughout the whole heat sink is constant, i.e. it is, say, 100 degree C in ever part so there is no temperature gradient across any of the fins or in the sink.

 

Of course this cannot be but I do not see where I have made my mistake. I have seen mention of a 2-Resistor component on some other disucssion but am not sure how to apply this.

 

I am running the study using an assembly of parts, one of which is the heat sink and another one of which is the LED COB package. I have modelled this as a single part made of silicon, i.e. the entire package, not just the chip. Perhaps this is wrong?

 

Really stuck here so any help would be really appreciated!

 

Thanks in advance!

 

Jamshid

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