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2D Axisymmetric and 2D simulation of permanent magnet

Posted 23 gen 2015, 19:27 GMT-5 Low-Frequency Electromagnetics, Mesh Version 5.2a 4 Replies

MuRGMac
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Hi,


I am trying to simulate magnetic fields from a permanent magnet in simple 2D and 2D axisymmetric configuration using magnetic field no current module but COMSOL is erroring out saying that the error is greater than tolerance. The configuration in 2D is a rectangular bar magnet and configuration in 2D axisymmetric is a rectangle offset from the axis (i.e. a ring shaped magnet in 3D). However, I have tested other configurations as well and the error stays the same

3D simulations are working out perfectly for any magnet geometry. I followed the steps for setting up the magnetic field in COMOSL tutorial for a horse-shoe magnet and got perfect results in 3D but when I apply same setup in 2D and 2D axisymmetric COMSOL is erroring out. I am attaching my 2d axisymmetric case (COMSOL V 5.0).

Can anyone please point out if there needs to be a different setup for 2D and 2D axisymmetric?
Any help is greatly appreciated

Thanks and regards,
Souvik.

Attachments:

4 Replies Last Post 3 apr 2017, 02:30 GMT-4
Wenzhi Yang
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Posted: 10 years ago 25 gen 2015, 08:15 GMT-5
hi,
I am interested in your problem, however ,i do not have COMSOL 5.0, do you have 4.4 or 4.3.
hi, I am interested in your problem, however ,i do not have COMSOL 5.0, do you have 4.4 or 4.3.
Mark Harradine
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Posted: 10 years ago 27 gen 2015, 02:34 GMT-5
I think you may be missing a Zero Magnetic Potential condition. You need to add this to a point on your axis of symmetry, as shown in the attached model.

I seem to remember getting the same error message before I added this condition.

I cannot check for sure, as my Comsol License Server is down at the moment.
I think you may be missing a Zero Magnetic Potential condition. You need to add this to a point on your axis of symmetry, as shown in the attached model. I seem to remember getting the same error message before I added this condition. I cannot check for sure, as my Comsol License Server is down at the moment.

Attachments:

Yani Deng
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Posted: 8 years ago 31 mar 2017, 00:19 GMT-4
Thank you very much for your suggestion of adding a Zero Magnetic Potential condition on one point.
I follow your suggestions and build a similar model of calculating force between two permanent magnets, however, the force one the small magnet is very sensitive to mesh, when I refine the mesh, the calculated force can jump from positive value to negative value?! Can you help me figure out why?? Thank you very much for your help!
I don't know why I couldn't attach files. Here is the model description:
1. Two magnets(One small, One big) surrounded by air
2. Materials: air and N52 permeability
3. BC: for two magnets, use Magnetic Flux Conservation, and use remnant flux density as constitutive law
add a Zero Magnetic Potential condition on one point.
use Force calculation to calculate the force on small magnet.
4. Mesh: I used physical controlled mesh, from normal to extremely mesh.
The calculated force varies very much for different mesh, and doesn't make any sense.
Thank you very much for your suggestion of adding a Zero Magnetic Potential condition on one point. I follow your suggestions and build a similar model of calculating force between two permanent magnets, however, the force one the small magnet is very sensitive to mesh, when I refine the mesh, the calculated force can jump from positive value to negative value?! Can you help me figure out why?? Thank you very much for your help! I don't know why I couldn't attach files. Here is the model description: 1. Two magnets(One small, One big) surrounded by air 2. Materials: air and N52 permeability 3. BC: for two magnets, use Magnetic Flux Conservation, and use remnant flux density as constitutive law add a Zero Magnetic Potential condition on one point. use Force calculation to calculate the force on small magnet. 4. Mesh: I used physical controlled mesh, from normal to extremely mesh. The calculated force varies very much for different mesh, and doesn't make any sense.
Mark Harradine
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Posted: 8 years ago 3 apr 2017, 02:30 GMT-4
The Force calculation can be very sensitive to the mesh density, particularly if your magnets only have a thin airgap between them. How many layers of elements do you have in the gap between the magnets? Are your results converging on a value as you increase the mesh density?
The Force calculation can be very sensitive to the mesh density, particularly if your magnets only have a thin airgap between them. How many layers of elements do you have in the gap between the magnets? Are your results converging on a value as you increase the mesh density?

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