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3D Electromagnet

Posted Sep 2, 2010, 6:38 a.m. EDT Low-Frequency Electromagnetics 2 Replies

mb
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Dear community,

I want to simulate an electromagnet in 3D using half symmetry. I'm interested in the Lorentz force distribution in the plate above, that forms due to B-field and the induced currents in the plate. (The B-field in the magnet core is not of interest.)


Now my question: The bc at the coil cross section is a current density of 1e+5 A/m^2. But obviously (see plot group 2d 4 - cross section of the coil), the real applied current density is about half that value. Any ideas why that happens?

I also tried to use electric potential as bc resulting in very low B-field.


Thanks.

Best regards
Marcel

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2 Replies Last Post Sep 2, 2010, 7:41 a.m. EDT
Edgar Kaiser
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Posted: 1 decade ago Sep 2, 2010, 7:36 a.m. EDT
Marcel,

I couldn't open your model in COMSOL40 but here may be one reason for your observation. If you model your coil with conductive material (e.g. copper) your external current density will be decreased by the induced current. You can assign very low or zero conductivity to the coil domain to avoid that.

Regards
Edgar
Marcel, I couldn't open your model in COMSOL40 but here may be one reason for your observation. If you model your coil with conductive material (e.g. copper) your external current density will be decreased by the induced current. You can assign very low or zero conductivity to the coil domain to avoid that. Regards Edgar
mb
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Posted: 1 decade ago Sep 2, 2010, 7:41 a.m. EDT
Thanks for your hint!

This is what I already did. Conductivity of the coil and the surrounding air volume is set to 1 S/m.


Regards, Marcel
Thanks for your hint! This is what I already did. Conductivity of the coil and the surrounding air volume is set to 1 S/m. Regards, Marcel

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