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How do I compare the voltage difference of 2 boundaries with respect to the position along it?

Posted Apr 26, 2016, 9:03 p.m. EDT Low-Frequency Electromagnetics, Geometry, Parameters, Variables, & Functions, Studies & Solvers Version 4.3 3 Replies

Stephen Gibellini
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Hello COMSOL users,

Im am trying to replicate the study attached that was performed at a COMSOL conference but i have ran into complications. (The file is attached below)
I don't understand how to get the voltage difference between 2 points on a boundary. These 2 points must be a part of the boundary (but not specifically defined) and the voltage differential I want to get has to lie directly across from it.
So say I'm working the 2D axial symmetrical plane and have a boundary at r .5 and another at .505. These lie directly across from each other and have the same dimension in z. Using an electrostatics module (or electric current) I apply a voltage to my structure and wish to know the difference in voltage in relation to the z component.

Please let me know if you have any ideas on how I should go about solving this. The paper says that I should use extrusion but I am not clear on how. I have read many different threads and COMSOL examples and still don't fully understand how to use it. I tried using the boundary probe but this did not seem helpful.

Note: I believe this paper has some mistakes in the writing.

Regards,
Stephen
3 Replies Last Post Apr 27, 2016, 1:21 p.m. EDT
Jeff Hiller COMSOL Employee

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Posted: 8 years ago Apr 27, 2016, 9:40 a.m. EDT
Hi Stephen,
I believe the authors of this paper are referring to Component Couplings of the Extrusion type. See COMSOL Multiphysics Reference Manual, version 5.2, page 281 and following.
Best,
Jeff
Hi Stephen, I believe the authors of this paper are referring to Component Couplings of the Extrusion type. See COMSOL Multiphysics Reference Manual, version 5.2, page 281 and following. Best, Jeff
Stephen Gibellini
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Posted: 8 years ago Apr 27, 2016, 12:44 p.m. EDT
Hi Jeff,

Firstly thank you for responding to my question. I am using student version 4.3 of COMSOL and do not have access to 5.2 . This paper was written in 2009 so I am assuming they did not use a version of COMSOL newer than 4.3 . Thank you again for your help.

Regards,
Stephen Gibellini
Hi Jeff, Firstly thank you for responding to my question. I am using student version 4.3 of COMSOL and do not have access to 5.2 . This paper was written in 2009 so I am assuming they did not use a version of COMSOL newer than 4.3 . Thank you again for your help. Regards, Stephen Gibellini
Jeff Hiller COMSOL Employee

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Posted: 8 years ago Apr 27, 2016, 1:21 p.m. EDT
The same concept existed back then as well. I no longer have version 4.3 on my machine so I can't tell you which page of the documentation to look up. If you do a Ctrl+F on the pdf of the Reference Manual for "component couplings" or "coupling operator", you should find it.

Best,
Jeff
PS: In case you communicate with the authors, and if they used a version prior to 4.0, the equivalent concept was called "extrusion coupling variables" back then. It was the same general capability but a bit tedious to use in some cases compared to what we have now, because you needed to create a separate extrusion coupling variable for each quantity you wanted to extrude, whereas now you can create a single operator and apply it with various arguments.
The same concept existed back then as well. I no longer have version 4.3 on my machine so I can't tell you which page of the documentation to look up. If you do a Ctrl+F on the pdf of the Reference Manual for "component couplings" or "coupling operator", you should find it. Best, Jeff PS: In case you communicate with the authors, and if they used a version prior to 4.0, the equivalent concept was called "extrusion coupling variables" back then. It was the same general capability but a bit tedious to use in some cases compared to what we have now, because you needed to create a separate extrusion coupling variable for each quantity you wanted to extrude, whereas now you can create a single operator and apply it with various arguments.

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