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Prescribing a current density in a coil in MFH
Posted 05.01.2018, 09:01 GMT-5 Low-Frequency Electromagnetics Version 5.2a 2 Replies
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Hello, I would like to prescribe a given (flat) current density in the single-turn winding of a coil in the mfh module (2D). There only seems to be the 'External current density' node for this, or I have overlooked something. If I do this, and specify a realistic (good) conductivity for the coil, there would be opposite induced currents in the coil, which nearly cancel the externally prescribed current. I can suppress the eddy currents by specifying unphysically low conductivity, but this would create very large electric fields in the conductor. What is the correct way to prescribe a given flat total current density within a coil in the mfh module? Thank you Daniel
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Daniel,
You should use "Coil" feature node, as shown in the attached image. This will account for induction currents in the coil, just make sure to mesh coil appropriately to resolve skin depth, especially if you are working with high frequencies.
Regards, Sergei
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Daniel,
Sorry, I overlooked that you are using Magnetic Field Formulation (mfh) physics interface. For the mfh interface, "Coil" feature is not available, but you can excite coil by prescribing the tangential component of the magnetic field on the line around the coil, as explained in the following model from the Model Library:
https://www.comsol.com/model/superconducting-wire-689
Regards, Sergei