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How to add a constant current boundary?

Posted Jul 7, 2010, 10:55 a.m. EDT 4 Replies

Li Zhang
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Hi,

I'm trying to apply a constant current, but I noticed I could only be able to add current density to a boundary. How am I supposed to solve this problem?

Thanks,
Li
4 Replies Last Post Jul 11, 2010, 12:12 a.m. EDT
Jie Xiang
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Posted: 1 decade ago Jul 7, 2010, 4:34 p.m. EDT
Maybe you can upload your mph file. I think it is easy to add a surface current density boundary condition in Comsol4.0.
Maybe you can upload your mph file. I think it is easy to add a surface current density boundary condition in Comsol4.0.
Li Zhang
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Posted: 1 decade ago Jul 7, 2010, 4:40 p.m. EDT

Maybe you can upload your mph file. I think it is easy to add a surface current density boundary condition in Comsol4.0.


Hi Jie,

Attached is the model file. Currently I just simply add voltage potential and ground to two terminals. But I would like to add a constant current to the model. I've got no idea how.

Thanks,
Li
[QUOTE] Maybe you can upload your mph file. I think it is easy to add a surface current density boundary condition in Comsol4.0. [/QUOTE] Hi Jie, Attached is the model file. Currently I just simply add voltage potential and ground to two terminals. But I would like to add a constant current to the model. I've got no idea how. Thanks, Li

Attachments:

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jul 10, 2010, 2:10 p.m. EDT
Hi

I have only my V4.0a available so I cannot read your 3.3 file. But I do not catch the full issue, you you have a conductor surface of lets say 2[mm^2] and you want to force a current of 10[A] then you have a current density of 10/2=5[A/mm^2] no ?

If you impose a voltage you need to adapt it depending on the impedance to get a constant current, though. That is what COMSOL is proposing for the "coil domain" boundary conditions.

You can have COMSOL to caluate the surfaces or the length with the Coupling inte3gration variables (_int of "1")

Good luck
Ivar
Hi I have only my V4.0a available so I cannot read your 3.3 file. But I do not catch the full issue, you you have a conductor surface of lets say 2[mm^2] and you want to force a current of 10[A] then you have a current density of 10/2=5[A/mm^2] no ? If you impose a voltage you need to adapt it depending on the impedance to get a constant current, though. That is what COMSOL is proposing for the "coil domain" boundary conditions. You can have COMSOL to caluate the surfaces or the length with the Coupling inte3gration variables (_int of "1") Good luck Ivar
Li Zhang
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Posted: 1 decade ago Jul 11, 2010, 12:12 a.m. EDT
Thanks, Ivar,

I solved the problem this way.

Li
Thanks, Ivar, I solved the problem this way. Li

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