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Conductive heat transfer in a via/cylinder
Posted 2020年10月20日 GMT-4 04:36 Heat Transfer Version 5.5 7 Replies
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Hello,
I am trying to learn COMSOL modelling and simulation. As my final objective is to simulate PCBs heat transfer, I am starting with a simple via. The idea is then to set the convection and radiation from my cylinder to be non-existant. I would like to then set a temperature and a heat flux to further find a thermal resistance of this via by using:
It seems that I don't understand how to set the boundaries for this. My idea was to set actually a "room temperature" of 25[degC] as initial condition and add a heat flux of Q at one of the edges of the cylinder. However, it returns the following error:
Failed to find a solution. The relative residual (4.1) is greater than the relative tolerance. There was a warning message from the linear solver. Iterative refinement triggered. Returned solution is not converged. Not all parameter steps returned.
I've set both my via radius and my heat flux to be parametric (from 0.05 mm to 0.15mm and 1 to 10W, respectively). You have my COMSOL file attached to this.
Thank you in advance.
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Guilherme,
in your model all boundaries except the heat sources are insulated. Therefore the temperature rises to infinity and breaks the solver. You need a heat sink. This can e.g. be a temperature boundary. The heat you bring in must go out somewhere.
Cheers Edgar
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
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Dear Edgard,
Thank you for the answer. Just so I see if I understand I should set one of my edges with a heat flux Q that I want to vary from 1 to 10 W and then set my remaining boundaries to a temperature? (e.g: 25 degC)
How I would see the temperature rise caused by this Q then?
EDIT: by doing as I exemplified above I can now properly simulate. My new question now is if I can somehow evaluate the points and values of my min and max temperatures (e.g: (1,1,1, 25) where 1,1,1 would be x,y,z and 25 would be the temperature).
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You can check the max/min operations in 'Nonlocal couplings' and respective Max/Min datasets in the postprocessing. Also point probes and point cut datasets may be of interest.
Cheers Edgar
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
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Dear Edgar,
I actually ran the simulation and extracted the results using a Derived Value and created a Surface Maximum. However this doesn't agree with my analytical model and I am not sure if then I am correctly extracting the value. In theory my thermal resistance would be given by
which for d = 0.1mm, k = 401 and t = 1mm would yield a thermal resistance of 317 degC/W, while from simulation I get around 2degC/W.
What I am doing wrongly here?
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Check if your model realizes this kind of thermal resistor. I think the barrel of the cylinder should be thermally isolated in this case.
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
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Thank you Edgar, it seems now that this works. This is my first try with COMSOL and in my mind I was doing so (but I ovewrote the isolation by setting a temperature boundary).
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Good to hear that it works for you now.
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com