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Modeling Coils in COMSOL

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I am trying to follow the Helmholtz Coil example in the model library for a rectangular coil form. I designed my rectangular coil form and imported it as a .stl file. I set the material to copper and set it up as a multi-turn coil domain. I have attached my model but I am having trouble getting the plot that was shown in the helmholtz coil example. I am also wondering if COMSOL can give a numerical readout of the magnetic field ad various points in space.

I have attached my model.


7 Replies Last Post 27.12.2015, 17:27 GMT-5
Edgar J. Kaiser Certified Consultant

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Posted: 1 decade ago 09.06.2014, 15:40 GMT-4

Michael,

you have a couple of problems in your model:

- There is no air domain around the coil
- Numerical coils need to have a constant cross section along the winding path (the corners in the rectangular shape of your coil violate that)
- An automatic current calculation subnode with insulation and input definition is needed

Refer to 'multiturn_coil_asymmetric_conductor' model in the model library to get the details.

Cheers
Edgar


--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Michael, you have a couple of problems in your model: - There is no air domain around the coil - Numerical coils need to have a constant cross section along the winding path (the corners in the rectangular shape of your coil violate that) - An automatic current calculation subnode with insulation and input definition is needed Refer to 'multiturn_coil_asymmetric_conductor' model in the model library to get the details. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com

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Posted: 1 decade ago 09.06.2014, 16:51 GMT-4
I have looked at the model in the library that you referenced but I am still a bit confused. I remade my model to have a constant cross section and I also thought that I surrounded the coils with an air domain. I think that I put in the current calculation subnode in the cross sectional area but it doesn't work like the library model.
I have looked at the model in the library that you referenced but I am still a bit confused. I remade my model to have a constant cross section and I also thought that I surrounded the coils with an air domain. I think that I put in the current calculation subnode in the cross sectional area but it doesn't work like the library model.


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Posted: 1 decade ago 09.06.2014, 16:51 GMT-4
I have looked at the model in the library that you referenced but I am still a bit confused. I remade my model to have a constant cross section and I also thought that I surrounded the coils with an air domain. I think that I put in the current calculation subnode in the cross sectional area but it doesn't work like the library model.
I have looked at the model in the library that you referenced but I am still a bit confused. I remade my model to have a constant cross section and I also thought that I surrounded the coils with an air domain. I think that I put in the current calculation subnode in the cross sectional area but it doesn't work like the library model.

Edgar J. Kaiser Certified Consultant

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Posted: 1 decade ago 10.06.2014, 02:48 GMT-4

There aren't any study steps in the new model you attached. Look into the example once more. You need a current calculation step and a stationary (in your case?) or frequency domain step.
Also giving a small conductivity to the air domain can be useful for solver stability. Sometimes also the Gauge Fixing for A-field is required to get the solver stable.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
There aren't any study steps in the new model you attached. Look into the example once more. You need a current calculation step and a stationary (in your case?) or frequency domain step. Also giving a small conductivity to the air domain can be useful for solver stability. Sometimes also the Gauge Fixing for A-field is required to get the solver stable. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com

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Posted: 1 decade ago 10.06.2014, 11:58 GMT-4
Thanks! I have gotten my model working a lot better by following your advice. I am curious as to weather I could model how the magnetic field in the coils would change through time as the coils were pulsed with current. I didn't find an example model that demonstrated this phenomena.
Thanks! I have gotten my model working a lot better by following your advice. I am curious as to weather I could model how the magnetic field in the coils would change through time as the coils were pulsed with current. I didn't find an example model that demonstrated this phenomena.

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Posted: 10 years ago 31.10.2014, 09:36 GMT-4
I'm new at COMSOL and I'm looking to study the magnetic field in between two rectangular coils. It seems that your model is a good start for me. Is it possible to share your last version of the model that works better according to your last post?

Thanks.
I'm new at COMSOL and I'm looking to study the magnetic field in between two rectangular coils. It seems that your model is a good start for me. Is it possible to share your last version of the model that works better according to your last post? Thanks.

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Posted: 9 years ago 27.12.2015, 17:27 GMT-5
hello Edgar J3. Kaiser I have a problem in the simulation of a coil in a pulsed excitaion you can please me helped by a model
hello Edgar J3. Kaiser I have a problem in the simulation of a coil in a pulsed excitaion you can please me helped by a model

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