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Remove the Default Magnetic Insulation Boundary Condition?

Posted Jun 24, 2016, 4:25 p.m. EDT 5 Replies

Desiree Johnson
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I am building a model that involves a square shaped coil (edges filleted) around a piece of iron, surrounded by a large cylinder of air. However I get incorrect results because the mf physics automatically adds a magnetic insulation boundary condition to all boundaries in the model (I do not want the magnetic insulation boundary condition on the coil boundaries). Is there a way to remove the default magnetic insulation BC and add my own (I see that I can add another magnetic insulation BC but I'm not sure how to remove the defaults)? Or is there another subnode that can remove it?
5 Replies Last Post Jun 28, 2016, 10:13 a.m. EDT
Jeff Hiller COMSOL Employee

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Posted: 8 years ago Jun 24, 2016, 4:39 p.m. EDT
Hello Desiree,
You cannot delete a default physics node: you over-ride it by applying some other setting to the same entity (domain, boundary, edge or point). See Introduction to COMSOL Multiphysics manual version 5.2a, page 37 and 112 for more details. All manuals are accessed through the File > Help > Documentation menu.
Best,
Jeff
Hello Desiree, You cannot delete a default physics node: you over-ride it by applying some other setting to the same entity (domain, boundary, edge or point). See Introduction to COMSOL Multiphysics manual version 5.2a, page 37 and 112 for more details. All manuals are accessed through the File > Help > Documentation menu. Best, Jeff
Desiree Johnson
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Posted: 8 years ago Jun 24, 2016, 5:14 p.m. EDT
Okay thank you. I will try to see which node can best fit my model.
Okay thank you. I will try to see which node can best fit my model.
Desiree Johnson
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Posted: 8 years ago Jun 27, 2016, 4:04 p.m. EDT
Basically I just want the magnetic insulation on the exterior boundaries (air). Which type of boundary condition is most suitable (I tried adding the magnetic potential boundary condition but I don't know the value of A) to remove the magnetic insulation from the all other boundaries. Additionally, I don't think perfect magnetic conductor boundary condition because I want current flowing through all other boundaries. I'm trying to understand the periodic (continuity and antiperiodicity) condition but am having some trouble. I'm just starting out with something simple like the model attached.
Basically I just want the magnetic insulation on the exterior boundaries (air). Which type of boundary condition is most suitable (I tried adding the magnetic potential boundary condition but I don't know the value of A) to remove the magnetic insulation from the all other boundaries. Additionally, I don't think perfect magnetic conductor boundary condition because I want current flowing through all other boundaries. I'm trying to understand the periodic (continuity and antiperiodicity) condition but am having some trouble. I'm just starting out with something simple like the model attached.

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Jens Krause
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Posted: 8 years ago Jun 28, 2016, 8:17 a.m. EDT
The last step in your geometry is "Form an Assembly". Why?

If you use "Form a union" all internal interfaces are continuously connected and the externals
have magnetic shielding as required.

If your really need the the assembly than you can a node "Continuity" and apply it to the "Identity Pair 1".

Regards

Jens
The last step in your geometry is "Form an Assembly". Why? If you use "Form a union" all internal interfaces are continuously connected and the externals have magnetic shielding as required. If your really need the the assembly than you can a node "Continuity" and apply it to the "Identity Pair 1". Regards Jens
Desiree Johnson
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Posted: 8 years ago Jun 28, 2016, 10:13 a.m. EDT
Thank you for your suggestion. A reason I used "Form Assembly" is that I thought it was needed whenever there were contacting surfaces. But all my geometry is stationary and defined correctly with the "Form Union" so I will go back to using that. Another reason I used the assembly was because in the actual model I am using, the "Form Union" kept showing an error. It was..."boolean geometry failed." I suppose I will just play with the repair tolerances and see if it works out.
Thank you for your suggestion. A reason I used "Form Assembly" is that I thought it was needed whenever there were contacting surfaces. But all my geometry is stationary and defined correctly with the "Form Union" so I will go back to using that. Another reason I used the assembly was because in the actual model I am using, the "Form Union" kept showing an error. It was..."boolean geometry failed." I suppose I will just play with the repair tolerances and see if it works out.

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