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Magnetic field resulting from a dipole
Posted Nov 28, 2012, 8:46 a.m. EST Low-Frequency Electromagnetics Version 4.3 5 Replies
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I've implemented an electric point dipole somewhere in a sphere made of 4 layers, each with a different conductivity.
I want to compute the electric currents and the magnetic field resulting from the dipole.
Which physics should I choose?
I already tried electric currents, but there is no way to plot or evaluate the magnetic flux density.
I also tried magnetic and electric fields, but if I implement the dipole in that model, the electric and the magnetic field are zero, which can't actually be wright.
So what can I do? Maybe I could choose electric currents and define the flux density by my own and plot/evaluate it afterwards.
Who has got a tip for me?
I have to add that I'm kind of a beginner in COMSOL.
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You might give a better description of your model.
Your dipole - is it some kind of current source? And is there a corresponding sink, e.g. a ground BC at the outer boundary of the sphere? If not, there will be no current flow and therefore no magnetic field.
The mef interface seems the correct choice to me, assumed that I understood your model right.
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Maybe you can explain that to me!
Normally, from the dipole results a potential and from the potential results an electric field. Then you can also compute the current density, depending on the different conductivities.
And if I have currents, there should be a magnetic field. If I treat my whole sphere as a space with epsilon0 and mu0, it should work.
But maybe with comsol it doesn't work that easy. As I said, I'm a beginner.
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So I guess there is maybe a problem with the way you modeled your dipole. If you are talking about a POINT dipole, how did you implement that. I mean the two poles should be separated or isolated in some kind of way.
You might model a small cylinder of isolating material, maybe 1 mm of diameter and 1 mm of length and assign the two circle areas two potentials, e. g. +1V and -1V...
Herzliche Grüße
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To implement the point dipole, I chose the one that's predefined, when you right-click magnetic and electric fields in your model and choose "points>electric point dipole". Then I defined the dipole moment, but then, as I said, didn't yield to any field.
I'll try out your suggestion, but maybe you've got an idea, why it doesn't work the way I did it first.
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