Union/Assembly

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I am doing magnetic field study and made one U structure rectangular coil with an Air Domain. When I am forming a union, current is flowing is 1 or 2 legs of the coil and not in all 3,and forming magnetic field according to those conductors. When I am forming assembly, magnetic field is not being generated in Air but current is flowing in every conductor, How to resolve this issue!!!



5 Replies Last Post Dec 20, 2025, 3:47 p.m. EST
Robert Koslover Certified Consultant

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Posted: 23 hours ago Dec 19, 2025, 6:20 p.m. EST
  1. I suggest you post your .mph file to the forum.
  2. I also suggest you form a union, not an assembly.

I suspect there is one or more errors in your model that can be revealed by inspecting your .mph file. Please post at least the one where you formed a union.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
1. I suggest you post your .mph file to the forum. 2. I also suggest you form a union, not an assembly. I suspect there is one or more errors in your model that can be revealed by inspecting your .mph file. Please post at least the one where you formed a union.

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Posted: 17 hours ago Dec 20, 2025, 12:30 a.m. EST
Updated: 17 hours ago Dec 20, 2025, 12:33 a.m. EST

Below is the attached file.

Also can you tell in union i am not able to select the output terminal of my coil. Thanks

Below is the attached file. Also can you tell in union i am not able to select the output terminal of my coil. Thanks


Robert Koslover Certified Consultant

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Posted: 7 hours ago Dec 20, 2025, 10:36 a.m. EST
  1. Your model has a "union" in it but you are actually applying "Form Assembly" anyway. You should have "Form Union" at the end of the geometry section. (See my note 3 below for more.)
  2. You have a U-shaped conductor that you are attempting to apply a current in to and out of that is an otherwise-isolated open-conducting path in free space! This is unphysical. If it solves at all, it will be difficult (for me, anyway) to properly understand the results obtained as representative of a physical reality. For what it is worth, I have shifted your cube over so that the current input/output connections are on one of the faces of the cube. Whether this represents the physics of your problem or not, I don't know, but at least it is a physically meaningful boundary condition.
  3. You have magnetic insulation boundary conditions on your conductor. That is unphysical also. Note: If you right-click on "Form Assembly" in the Model Builder and then go to the Settings panel, you can change the Action (under "Form Union/Assembly") to "Form Union." This change will eliminate the incorrect magnetic insulation boundary conditions that the code applied to your conductor when you used "Form Assembly." Note: You should always check that your boundary conditions represent physically meaningful/correct conditions, or else your results (if any) will be wrong.
  4. There is a 1mm edge block (your "Block 2") in the middle of your model that seems to have no purpose at all. I'm simply ignoring it, but unless it has a purpose, you should get rid of it.
  5. I've attached a modified model (I cleared the solution to save space; you will need to execute it to see the results) that both solves and gives a meaningful picture (snapshot attached). But you may need to make additional changes, and possibly substantial ones, to get it to represent your real world problem (that is, assuming you are trying to model a real-world problem). I hope this helps.
-------------------
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
1. Your model has a "union" in it but you are actually applying "Form Assembly" anyway. You should have "Form Union" at the end of the geometry section. (See my note 3 below for more.) 2. You have a U-shaped conductor that you are attempting to apply a current in to and out of that is an otherwise-isolated open-conducting path in free space! This is *unphysical*. If it solves at all, it will be difficult (for me, anyway) to properly understand the results obtained as representative of a physical reality. For what it is worth, I have shifted your cube over so that the current input/output connections are on one of the faces of the cube. Whether this represents the physics of your problem or not, I don't know, but at least it is a physically meaningful boundary condition. 3. You have magnetic insulation boundary conditions on your conductor. That is unphysical also. Note: If you right-click on "Form Assembly" in the Model Builder and then go to the Settings panel, you can change the Action (under "Form Union/Assembly") to "Form Union." This change will eliminate the incorrect magnetic insulation boundary conditions that the code applied to your conductor when you used "Form Assembly." Note: You should *always* check that your boundary conditions represent physically meaningful/correct conditions, or else your results (if any) will be wrong. 4. There is a 1mm edge block (your "Block 2") in the middle of your model that seems to have no purpose at all. I'm simply ignoring it, but unless it has a purpose, you should get rid of it. 5. I've attached a modified model (I cleared the solution to save space; you will need to execute it to see the results) that both solves and gives a meaningful picture (snapshot attached). But you may need to make additional changes, and possibly *substantial* ones, to get it to represent your *real world* problem (that is, assuming you are trying to model a real-world problem). I hope this helps.


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Posted: 3 hours ago Dec 20, 2025, 1:55 p.m. EST

As this is a COMSOL 6.4 file, and I have COMSOL 6.0 version, can i convert this is to 6.0 or you can send a 6.0 file.

Thanks a lot

As this is a COMSOL 6.4 file, and I have COMSOL 6.0 version, can i convert this is to 6.0 or you can send a 6.0 file. Thanks a lot

Robert Koslover Certified Consultant

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Posted: 1 hour ago Dec 20, 2025, 3:47 p.m. EST
Updated: 54 minutes ago Dec 20, 2025, 4:12 p.m. EST

Sorry, that's too far back. If you or your organization have an active license, I encourage you to upgrade your software to v6.4 . Meanwhile, you should (probably) be able to make the changes I already described in the notes above. Or perhaps you can find someone else around with some experience in this software, to help you. Consider also looking at simple coil examples in the Comsol Application Library.

-------------------
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
Sorry, that's too far back. If you or your organization have an active license, I encourage you to upgrade your software to v6.4 . Meanwhile, you should (probably) be able to make the changes I already described in the notes above. Or perhaps you can find someone else around with some experience in this software, to help you. Consider also looking at simple coil examples in the Comsol Application Library.

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