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Simulating magnetic fields induced by alternating current in figure 8 coil?
Posted 1 nov. 2016, 00:55 UTC−4 Low-Frequency Electromagnetics, Geometry, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 5.2 2 Replies
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Hi,
I'm working on an own project to simulate various things with figure 8 coil which is rather new coil type to be used in medical pain treatment. I'm still rather new to COMSOL and been working with this for 2 weeks full day now but I just can't find a way to get past this phase.
Similarly, as with other coil types, we create AC (in this case f=3,15kHz and I=3kA) to run through the coil conductor (made out of copper, dimensions 8mm(hight) x 3mm(width)) and to induce magnetic field which in turn induces electric field in brain's cerebral cortex.
Look below for the picture of the coil that I modeled for the simulations.
If anyone would have any clue or hint for creating above-mentioned sinusoidal AC and also the magnetic field that is induced by it, I would be extremely grateful!
Currently I have been trying to get this going using electric current (ec) and magnetic field (mf) physics modules combined and also magnetic and electric fields (mef) module, but yeah... haven't found the solution...
Thanks for the help in advance and please, ask for any specifying questions if needed!
I'm working on an own project to simulate various things with figure 8 coil which is rather new coil type to be used in medical pain treatment. I'm still rather new to COMSOL and been working with this for 2 weeks full day now but I just can't find a way to get past this phase.
Similarly, as with other coil types, we create AC (in this case f=3,15kHz and I=3kA) to run through the coil conductor (made out of copper, dimensions 8mm(hight) x 3mm(width)) and to induce magnetic field which in turn induces electric field in brain's cerebral cortex.
Look below for the picture of the coil that I modeled for the simulations.
If anyone would have any clue or hint for creating above-mentioned sinusoidal AC and also the magnetic field that is induced by it, I would be extremely grateful!
Currently I have been trying to get this going using electric current (ec) and magnetic field (mf) physics modules combined and also magnetic and electric fields (mef) module, but yeah... haven't found the solution...
Thanks for the help in advance and please, ask for any specifying questions if needed!
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2 Replies Last Post 4 nov. 2016, 01:52 UTC−4
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Posted:
8 years ago
1. Quick/obvious question: I can see the coil in your picture. But I don't see any computational space around it! Did you include a large/generous 3D computational volume around your coil or not? If not, then this is your biggest mistake. You absolutely MUST have a computational volume surrounding your coil, so you can model the magnetic field within that space. And by the way, make sure that volume is large enough that its boundaries (with conditions you must specify) do not severely perturb the actual fields of interest to you, in their locations of interest.
2. The two ends of your coil do not appear to be joined via any kind of port. You probably need to bring them together and connect them with a port, across which you can then apply a source (such as a voltage or current source). Consider using a lumped element port. There are various alternative ports you could also use. See the help system.
3. Your mesh looks too coarse, to me.
OK, fixing those items should get you closer to your goal. Good luck.
2. The two ends of your coil do not appear to be joined via any kind of port. You probably need to bring them together and connect them with a port, across which you can then apply a source (such as a voltage or current source). Consider using a lumped element port. There are various alternative ports you could also use. See the help system.
3. Your mesh looks too coarse, to me.
OK, fixing those items should get you closer to your goal. Good luck.
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Posted:
8 years ago
Hi Robert and thank you for replying!
I was well aware of the need of boundary and intentionally planned to leave it out as long as I would figure out how to get the current going first. Anyway, I now implemented it.
The mesh looks coarse because I'm using just a laptop for working. That model is low resolution version made from the one with better resolution. I tried using the latter one but the memory needs for that would have been above 16GB of virtual and physical memory which gives memory error when calculating anything. The low resolution model needs only about 2GB. The low resolution works just fine for this moment as it's faster to calculate and check if the methods work. If I get everything to work together nicely, I will try to implement higher resolution mesh.
I'm using i5-6200U 2,3GHz, 6GB of RAM and intel HD Graphics 520 with 1GB of memory... In case you're interested. Not a powerhouse but fast and does nicely what it needs to do.
As for the lumped element port: What do you mean by that? In the selection list of magnetic fields (mf) module, I can only find lumped port and lumped element but not lumped element port. The documentation really doesn't explain the port-systems very clearly in my opinion. There is hardly any practical examples about implementing those.
I have a couple of questions still:
What physics module do you think I should use for getting the port? Should the model ends be physically connected (and for what reason)? Also, there's basically no existing tutorials for AC so I would be really grateful if you could point me to the right direction on implementing that!
Once again, thank you for your help!
I was well aware of the need of boundary and intentionally planned to leave it out as long as I would figure out how to get the current going first. Anyway, I now implemented it.
The mesh looks coarse because I'm using just a laptop for working. That model is low resolution version made from the one with better resolution. I tried using the latter one but the memory needs for that would have been above 16GB of virtual and physical memory which gives memory error when calculating anything. The low resolution model needs only about 2GB. The low resolution works just fine for this moment as it's faster to calculate and check if the methods work. If I get everything to work together nicely, I will try to implement higher resolution mesh.
I'm using i5-6200U 2,3GHz, 6GB of RAM and intel HD Graphics 520 with 1GB of memory... In case you're interested. Not a powerhouse but fast and does nicely what it needs to do.
As for the lumped element port: What do you mean by that? In the selection list of magnetic fields (mf) module, I can only find lumped port and lumped element but not lumped element port. The documentation really doesn't explain the port-systems very clearly in my opinion. There is hardly any practical examples about implementing those.
I have a couple of questions still:
What physics module do you think I should use for getting the port? Should the model ends be physically connected (and for what reason)? Also, there's basically no existing tutorials for AC so I would be really grateful if you could point me to the right direction on implementing that!
Once again, thank you for your help!