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Hard Magnetic Field

Posted 15 févr. 2012, 22:17 UTC−5 Low-Frequency Electromagnetics Version 4.2a 5 Replies

Zafrullah Jagoo
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Hello everyone,
I am new to comsol and I am still trying to find my way through.

I am in the process of simulating the magnetic field of a geometry like the letter 'C'. The current is going to flow from the top end of the C and the ground is at the bottom of the C.

i41.tinypic.com/2ivxz6h.jpg

I am trying to get the magnetic field of this setup. The current will not be uniform thoughtout the ring so it is difficult to define the current density properly. Can anyone please guide me to get the magnetic field?
Thank you.
Regards
5 Replies Last Post 17 févr. 2012, 12:03 UTC−5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 16 févr. 2012, 02:23 UTC−5
Hi

if its a bulk connector in the chape of a "C" and you travel with a current from the two end points, the easiest is to apply a constant current sorce (terminal type) to one boundary and GND to the other, and leave COMSOL calculate the true current flow in the bulk material. But in 3D you need to get the current "in" and "out" of your volume, while still leaving air/vacuum for the field to loop around. I'm not sure how to do that as a current source cannot appear from nothing in a 3D space, you need a correct "loop"

--
Good luck
Ivar
Hi if its a bulk connector in the chape of a "C" and you travel with a current from the two end points, the easiest is to apply a constant current sorce (terminal type) to one boundary and GND to the other, and leave COMSOL calculate the true current flow in the bulk material. But in 3D you need to get the current "in" and "out" of your volume, while still leaving air/vacuum for the field to loop around. I'm not sure how to do that as a current source cannot appear from nothing in a 3D space, you need a correct "loop" -- Good luck Ivar
Edgar Kaiser
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Posted: 1 decade ago 16 févr. 2012, 03:25 UTC−5

In the picture it looks like the 'C' has a circular shape. If this is the case, the expression for an external current density is fairly easy.

Cheers
Edgar
In the picture it looks like the 'C' has a circular shape. If this is the case, the expression for an external current density is fairly easy. Cheers Edgar
Zafrullah Jagoo
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Posted: 1 decade ago 16 févr. 2012, 14:01 UTC−5
Thanks for your reply.

The current density is easy to calculate if the current flow is uniform inside the C shape. But I suspect this is never going to be the shape as current does not flow uniformly in sheets specially with the probe positioned like that. That is the main reason I wanted to find a way for COMSOL to automate the current like Ivar said, but the question is how to do it!

I think the best bet is to find the magnetic field in 2D.

Regards
Thanks for your reply. The current density is easy to calculate if the current flow is uniform inside the C shape. But I suspect this is never going to be the shape as current does not flow uniformly in sheets specially with the probe positioned like that. That is the main reason I wanted to find a way for COMSOL to automate the current like Ivar said, but the question is how to do it! I think the best bet is to find the magnetic field in 2D. Regards
Ralf Tschiesche
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Posted: 1 decade ago 17 févr. 2012, 03:48 UTC−5
Hi!

Maybe this will be a good start for your model:
www.comsol.com/community/forums/general/thread/25669/

Ralf
Hi! Maybe this will be a good start for your model: http://www.comsol.com/community/forums/general/thread/25669/ Ralf
Zafrullah Jagoo
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Posted: 1 decade ago 17 févr. 2012, 12:03 UTC−5
Thanks Ralf. I will try it and let you know how it goes.
Thanks Ralf. I will try it and let you know how it goes.

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