Heat sink simulation

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diegobdc
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Joined: 27 Jan 2016, 13:23
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Heat sink simulation

Post by diegobdc »

Hi guys, I'm new with Elmer (i've previously worked with Comsol and Ansys). I want to simulate the heat dissipated by a finned heat sink.
My problem is how to couple solvers, because as heat source I have a heat flux in Watts on the base of the heat sink.
This means that I have to firtsly simulate heat conduction in the heat sink, and after, the natural convection of air. So I have 3 solvers. Heat sink's Heat Equation (3), air's Heat Equation (2)and air's NS Equation (1). How do I couple them?

Equation 1
Name = "Heat-solid"
Active Solvers(1) = 3


Equation 2
Name = "Heat & Flow-air"
Convection = Computed
Active Solvers(3) = 3 2 1
End

Is it correct this way?


Another doubt is the boundary condition of the heat sink-air interface. ¿What bc should I use? NoSlip wall? My goal is to obtain heat transfer (heat transfer coefficient to be able to compare different heat sink geometries)and heatsink's temperature distribution.
mzenker
Posts: 1999
Joined: 07 Dec 2009, 11:49
Location: Germany

Re: Heat sink simulation

Post by mzenker »

Hi,

I advise you to use ElmerGUI at least as starting point. To couple solvers you just activate (i.e. check) them, so that they are active within the same "Equation". Different equations make sense if you need different solver configurations in different regions of your geometry.

I assume that you have looked into the documentation? The Solver Manual, Models Manual, ElmerGUI Manual and maybe the Tutorials are those you might want to consult if you need more information.

HTH,

Matthias
raback
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Re: Heat sink simulation

Post by raback »

Hi

You should rather use the same Heat equation for the two domains. The N-S equation will be solved iteratively with the Heat equation and hope to converge. With smaller timesteps you should be able to do so. The probably problems are related to the different timescales. Some tricks may be needed to overcome them.

-Peter
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