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Small Copper Wire Coil Producing Magnetic Field

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Hey all,

I'm pretty new to COMSOL, but I tried to build a very simple model which has a small, copper wire loop. The hope is that when a current is run through the loop there should be a larger magnetic field in the CENTER of the loop. Unfortunately this sort of "lensing" effect is not observed. I have consulted the model builder files both the current carrying wires model and the helmholtz coil model without being able to figure out whats wrong.

When I define the model I simply draw the parallel wires that bring current, and then a small loop and since I'm using the magnetic fields as my physics I then define the domains that make up the coil as having a current density in x,y,z under external current density. When I solve, I am able to produce a thermal map of the flux but it doesn't seem to make sense, as it implies the highest flux is along the wires and when I change it to magnetic field, it shows some nonsensical surface map that I'm having trouble believing. I would like to be able to produce data of the magnetic field gradient, the magnetic field, the heat produced by the sample when it's running, and the force produced by the wire, but I still haven't been able to make any reasonable results with the model I have. I fear that I may have somehow defined the current density incorrectly, but I'm not sure how. I also tried to build the model in 3D with similar results. I have attached the file, any help is always greatly appreciated.

Regards


4 Replies Last Post 20 juil. 2012, 09:57 UTC−4

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Posted: 1 decade ago 27 janv. 2012, 07:35 UTC−5
Hi!

The current density components in your model are unreal: same value for x,y,z in the complete conductor.
Next thing is, that in 2D your ring is more a endless tube (1m length).
Attached a quick-and-dirty model with MEF in 3D. Current is connected to ground and terminal to ends of wire (find in "magnetic insulation").
Sorry: model in 4.2a...

Ralf
Hi! The current density components in your model are unreal: same value for x,y,z in the complete conductor. Next thing is, that in 2D your ring is more a endless tube (1m length). Attached a quick-and-dirty model with MEF in 3D. Current is connected to ground and terminal to ends of wire (find in "magnetic insulation"). Sorry: model in 4.2a... Ralf


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Posted: 1 decade ago 27 janv. 2012, 18:25 UTC−5
Thanks,

I had thought to try and attach current probes but wasn't sure how. Your model seems much more reasonable, and I agree that the definition of current density in x,y,z never sat well with me. Thanks for the help, I'll see if anybody else on campus has 4.2a, but I think the things that you mentioned and the model will be of great help.

Regards
Thanks, I had thought to try and attach current probes but wasn't sure how. Your model seems much more reasonable, and I agree that the definition of current density in x,y,z never sat well with me. Thanks for the help, I'll see if anybody else on campus has 4.2a, but I think the things that you mentioned and the model will be of great help. Regards

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Posted: 1 decade ago 27 févr. 2012, 16:25 UTC−5
Hi,

I have downloaded the loop_wire02.mph model, but when I try opening in 4.2 it fails to open.

Please could you re-upload.

Many Thanks.
Tom
Hi, I have downloaded the loop_wire02.mph model, but when I try opening in 4.2 it fails to open. Please could you re-upload. Many Thanks. Tom

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Posted: 1 decade ago 20 juil. 2012, 09:57 UTC−4

Dear all ,
I am doing simulation of a single coil to find differnt parameters like Magnetic field intensity (H) , Inductance of coil , i excite the coil with single turn of coil with currnet 1 A , The magnetic field intensity of a coil is H= I/2r , where I is current of coil and r is radius of coil
If i take radius is 0.35m and current of coil 1 A , i should get H= 1.42 A/m , but i am not getting and getting less ...could tell the what is problem and solution
Model is attached
--
kishore Naik Mude
Dear all , I am doing simulation of a single coil to find differnt parameters like Magnetic field intensity (H) , Inductance of coil , i excite the coil with single turn of coil with currnet 1 A , The magnetic field intensity of a coil is H= I/2r , where I is current of coil and r is radius of coil If i take radius is 0.35m and current of coil 1 A , i should get H= 1.42 A/m , but i am not getting and getting less ...could tell the what is problem and solution Model is attached -- kishore Naik Mude

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