Magnetodynamic equation

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Roland
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Magnetodynamic equation

Post by Roland »

Hi,
When working at high frequencies it is very convenient in electromagnetics, as the electromagnetic skin depth is very small compared with the geometric dimensions, to solve only for the surface of the conducting bodies by using the "Impedance Boundary Condition" BC. So it is no more necessary to mesh the inside of the conductiong bodies,which saves a lot of meshes and a lot of computing time.
Is it possible to use such "Impedance Boundary Condition" BC in the Elmer Magnetodynamics equation?
Thanks for your help!
Roland
raback
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Re: Magnetodynamic equation

Post by raback »

Hi Roland,

You are right. We should add this. It is basically obvious extension for induction heating problems, we just have been quite focused on electrical machines.

Could you give the desired formula and naming conventions?

-Peter
Roland
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Re: Magnetodynamic equation

Post by Roland »

Hi Peter,
In Comsol (I am a Comsol user but am very interested in Elmer) the surface relation between E(electric field), Es(source electric field),H(magnetic field), is attached in the IBC_equation.jpg file.
As you can understand it would be very useful to have this add in the (2D and 3D) electromagnetics equation, since, in our high frequency induction heating processes, we use very often this interesting BC which saves a lot of meshes and computer solve time!
Don't hesitate to contact me and I hope that Elmer will soon offer this IBC possibility!
We keep us informed.
Best regards
Roland
Attachments
IBC_equation.JPG
IBC_equation.JPG (17.01 KiB) Viewed 3920 times
mzenker
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Re: Magnetodynamic equation

Post by mzenker »

Hi,

this reminds me a discussion some time ago on a new feature permitting to give a surface a thickness and use it as a body, implemented for the heat equation viewtopic.php?f=11&t=4210#p14890. Perhaps I misunderstood, but would Roland's request mean to extend that feature to the Magnetodynamics solver?
If so, could it also be used in the Static Current solver? This is something that would be very helpful for me as I sometimes deal with currents in thin metallic layers mounted on a thicker body.
Are the relevant changes to be made in the specific Solver or in the ElmerSolver core?

Matthias
Roland
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Re: Magnetodynamic equation

Post by Roland »

Hi,
Yes one can consider that the IBC in Magnetodynamics is a kind of extension of the "surface thickness" in heat transfer. This IBC can be used in high frequency (I don't think it works for the Static Current Solver) since the electromagnetic skin depth is small enough to consider that all the electric phenomena (induced currents, magnetic field, electric field) are concentrated in this small skin depth on the surface of the bodies.
Concerning the thin metallic layers that you mention, there is an extension of the IBC which is the "Transition Boundary Conditions" (TBC) based on propagating waves (with reflected and transited waves through the layer like in optics) which is implemented in Comsol and works very well. Thes BC's would be very useful in Elmer's Magnetodynamic equation...
We keep in touch
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