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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Error with Helmholtz Coil

Posted 2014年7月11日 GMT-4 08:46 Version 4.4 2 Replies

Nidhi Sinha
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I am trying to create a model to get a magnetic field profile using COMSOL version 4.4. I use the steps which are there in the tutorial for simulation of Helmholtz coil with a few changes. The dimensions are in cm and I am trying to do it in frequency domain so that I can pass AC current. The value of current is 0.25mA and frequency is 500 Hz. I am getting the following error

Failed to find a solution for the initial parameter.
Matrix has zero on diagonal.
Returned solution is not converged.

Can someone tell me why is it so or do I have to make some changes to make sure that I pass AC current and not DC in the coil.
I have attached the file with this email.

Thanks

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2 Replies Last Post 2014年7月14日 GMT-4 07:10
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago 2014年7月11日 GMT-4 09:09
Hi,

here are some comments on your model:

- I don't understand the frequency setting. If you want to use 500 Hz you only have to set the frequency domain study to 500. A range can be used to do a parameter study over different frequencies.
- You have to use 'Gauge fixing for A-field' in all domains
- Use the direct solver instead of the iterative one.

Cheers
Edgar
--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hi, here are some comments on your model: - I don't understand the frequency setting. If you want to use 500 Hz you only have to set the frequency domain study to 500. A range can be used to do a parameter study over different frequencies. - You have to use 'Gauge fixing for A-field' in all domains - Use the direct solver instead of the iterative one. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Nidhi Sinha
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Posted: 1 decade ago 2014年7月14日 GMT-4 07:10
I am not very familiar with comsol. Can you please tell me where or how can I change itiraqtive solver to direct one and use gauge fixing for A field.
I am not very familiar with comsol. Can you please tell me where or how can I change itiraqtive solver to direct one and use gauge fixing for A field.

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