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Small air gap boundary condition
Posted 2 oct. 2024, 12:49 UTC−4 Electromagnetics, Modeling Tools & Definitions, Physics Interfaces Version 6.1 6 Replies
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I am simulating some induced eddy currents in a copper plate suspended above an alternating magnetic dipole (10 kHz). I want to split the copper plate into two halves and apply a boundary condition (or equivalent) between the two halves which simulates the copper plates not quite touching and prevents current from flowing across/normal to the boundary condition.
I have had success by creating a physical air gap between the plates (you can see the thin domain along the center of the plate which I have been setting as air material), but not by setting a boundary condition.
In my model at the moment I have a 'Magnetic Insulation 2' boundary condition which I am hoping to replace for another which will give me the desired properties.
What is best practice for simulating small air gaps like this specifically to prevent eddy current flow?
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Surely you just need to assign Air to domain 7? A magnetic insulation BC is not representative of the physical situation you are trying to re-create.
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Surely you just need to assign Air to domain 7? A magnetic insulation BC is not representative of the physical situation you are trying to re-create.
Hi Mark, cheers for the feedback. Yes the magnetic insulation BC is what I wanted to replace with something that IS representative ( I just had it in there as a leftover failed attempt ). As I mentioned I have tried assigning the central domain 7 to air and achieved good results.
I should have said: I am using this model as a simplified case of a larger more complex one. The air gaps in the larger model are orders of magnitude thinner than domain 7 and I don't think it is best practice to mesh this?
There must be a condition that I can impose on the boundary between the two halves of the plate which provides the same impedance (or equivalent) that a 0.01 mm air gap would? Will it require linking a different physics module into the magnetic fields module such as the Electric Currents module?
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Surely you just need to assign Air to domain 7? A magnetic insulation BC is not representative of the physical situation you are trying to re-create.
Good point! Assigning a gas to Domain 7 makes sense to more accurately represent the physical environment. The use of magnetic insulators may cause inaccurate results. This is because they do not reflect behavior in the real world.
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Surely you just need to assign Air to domain 7? A magnetic insulation BC is not representative of the physical situation you are trying to re-create.
Good point! Assigning a gas to Domain 7 makes sense to more accurately represent the physical environment. The use of magnetic insulators may cause inaccurate results. This is because they do not reflect behavior in the real world.
Hi Joshua, as i have explained I am aware that that the magnetic insulator BC is wrong in this case and I am also aware that assigning a gas to domain 7 yields good results.
I want to know if I can apply constraints to the boundary between the two halves of the plate, not domain 7, which will have the same affect as assigning air to domain 7.
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Hello, You can use the "Passive Conductor" domain feature in the Magnetic Fields interface to achieve perfect insulation between adjacent domains. If you want imperfect insulation, then you will need to use the Magnetic and Electric Fields interface and use the Magnetic Continuity > Contact Impedance boundary condition.
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Hello, You can use the "Passive Conductor" domain feature in the Magnetic Fields interface to achieve perfect insulation between adjacent domains. If you want imperfect insulation, then you will need to use the Magnetic and Electric Fields interface and use the Magnetic Continuity > Contact Impedance boundary condition.
Hi Walter, thanks for your response. I have used the Passive Conductor feature in a further simplified model and this has achieved the results I wanted - great. The only down side is that the solution only seems to converge for very simple models. I have attached two models: the one is simplified and takes around 6 minutes to solve on my machine, the other will not converge even when left chewing overnight. Are you able to spot any mistakes I have made in the setup? Another thing worth mentioning is that in the simple file which does converge after 6 minutes - if I use a physical meshed air gap it solves orders of magnitude faster. I imagine the reason is that using the passive conductor constraints means the problem is harder to solve and it has to switch to a different numerical solver which takes far longer than the standard solver?
Thanks