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Heat Transfer. Surface-to-surface radiation node
Posted 03.04.2014, 08:14 GMT-4 Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD) Version 4.3a 3 Replies
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I'm a physics student and I'm trying to simulate with COMSOL the heat behavior of a chip connected to a CdTe detector. In my geometry I have domains that are not touching each other and I would like to take into account how they are heating up each other due to radiation. Since they are so close to each other, I think I should use the surface-to -surface radiation node (instead of the surface-to-ambient radiation node), but I do not understand how to use it. The surface-to-surface node does not ask me to give the distance between surfaces. How can I be sure that COMSOL does not only calculate the radiation coming from the surfaces, but also how the surfaces are heated up from receiving the radiation from other surfaces?
It would be helpful if somebody could explain me how to do this.
Thank you in advance,
David
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You only have to define the external temperature (far away your device) and the emissivities of your surfaces, Comsol will done everything else.
Try to make simple tests if you are worry about this.
Julien
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First of all thank you for your response. Now I understand how to use the surface-to-surface node.
These bodies, which are not touching, are not only heating up each other due to radiation, but also due to the bulk motion of the heated air between them (convection). As far as I know I have to use the internal natural convection node (if the air is not moving). I also not understand how to use it. For example, in the case that I have two parallel and horizontal surfaces so close, which boundaries and parameters do I have to introduce? This node is asking me to give the plate distance but I do not understand between which of the boundaries is COMSOL taking this distance.
Thank you again in advance,
David
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You have 2 choices;
- you can add a gas domain where you couple fluid dynamic and heat transfert (difficult)
- or you can calculate Nusselts and Grashof numbers for estimate heat transfert coefficient h[W/(m^2
*K)] and applicate them on external boundaries (look for in litterature the right case for your study). In this case you don't need a representation of the fluid domain (easy to converge)
At least you must first start with a simple simulation
Julien