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AC/DC -> Electrostatic : set an electric Potential on Domains

Posted Nov 9, 2011, 5:47 a.m. EST Plasma Physics 6 Replies

Raed Jaarah
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Hallo,

in the AC/DC Modul for electrostatic study is it posible to set a Domain as electric potential ?
in my Model i designed some electrical conductors and i can only to set the electric potential on the Boundaries. but i wont to set the conductor (domain) on the potential ?

Do anyone have an Idee ?

Thanks,
6 Replies Last Post Nov 13, 2011, 2:58 p.m. EST
Edgar Kaiser
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Posted: 1 decade ago Nov 9, 2011, 9:40 a.m. EST
Hi,

to my knowledge it is not possible. But even if it was possible, it doesn't make a difference. If the domain is a conductor, it will be at the potential of the boundary as a whole.

Cheers
Edgar
Hi, to my knowledge it is not possible. But even if it was possible, it doesn't make a difference. If the domain is a conductor, it will be at the potential of the boundary as a whole. Cheers Edgar
Raed Jaarah
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Posted: 1 decade ago Nov 9, 2011, 11:20 a.m. EST
thanks edgar.
i know that dosn´t make a difference. i asked because i am working with Matlab Livelink. so it is more practical for me to use the domains, because the circle in COMSOL have 4 boundaries, so that i have everytime to look witch boundaries i have to choose for the conductors.

Regards
thanks edgar. i know that dosn´t make a difference. i asked because i am working with Matlab Livelink. so it is more practical for me to use the domains, because the circle in COMSOL have 4 boundaries, so that i have everytime to look witch boundaries i have to choose for the conductors. Regards
Edgar Kaiser
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Posted: 1 decade ago Nov 9, 2011, 11:27 a.m. EST
Terry,

yes I see, I also would like to have an option to select all boundaries on a domain automatically some way.

Cheers
Edgar
Terry, yes I see, I also would like to have an option to select all boundaries on a domain automatically some way. Cheers Edgar
John H.
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Posted: 1 decade ago Nov 9, 2011, 11:33 a.m. EST
Then you could use the function mphgetadj(...) that is part of Comsol's Matlab interface. It returns a list of the adjacent boundaries for a given domain, relieving you of the burden to look up these pesky numbers on your own.

Comsol's GUI, by the way, as of version 4.2 provides a similar feature with "Adjacent" selections.
Then you could use the function mphgetadj(...) that is part of Comsol's Matlab interface. It returns a list of the adjacent boundaries for a given domain, relieving you of the burden to look up these pesky numbers on your own. Comsol's GUI, by the way, as of version 4.2 provides a similar feature with "Adjacent" selections.
Shoval Zoran
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Posted: 1 decade ago Nov 13, 2011, 9:20 a.m. EST
In AC/DC, I'm having sort of a similar problem, except for a different reason:

In various ACDC physics, one can only place a boundary terminal/ground as a part of the insulation - as an overriding option to the electric insulation. However, not always I want the current to go that way; I want to have potential on a specific place, and I can't do that. I figured using initial conditions for domains, but that would cause a time-dependent model, since eventually the potential will even out. I want a terminal and a ground, in MEF for example. is there a way to do this?

thanks.
In AC/DC, I'm having sort of a similar problem, except for a different reason: In various ACDC physics, one can only place a boundary terminal/ground as a part of the insulation - as an overriding option to the electric insulation. However, not always I want the current to go that way; I want to have potential on a specific place, and I can't do that. I figured using initial conditions for domains, but that would cause a time-dependent model, since eventually the potential will even out. I want a terminal and a ground, in MEF for example. is there a way to do this? thanks.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 13, 2011, 2:58 p.m. EST
Hi

but in MEF: you solve for the scalar V and the vector A.
So how can you simulate a model (physicslly correct I mean) if you have the spontaneous appearance of a current (or voltage hence current via the resistance) source in the midle of your geometry, as for a port ?

For me, you need the complete, closed current loop to solve correctly A and link to V.

Therefore in EM (different from only ES or EC) one should think closed current loops, and vacuum or material volume to close the B-H fields

I'm not sure how to represent that with a "port" EM

--
Good luck
Ivar
Hi but in MEF: you solve for the scalar V and the vector A. So how can you simulate a model (physicslly correct I mean) if you have the spontaneous appearance of a current (or voltage hence current via the resistance) source in the midle of your geometry, as for a port ? For me, you need the complete, closed current loop to solve correctly A and link to V. Therefore in EM (different from only ES or EC) one should think closed current loops, and vacuum or material volume to close the B-H fields I'm not sure how to represent that with a "port" EM -- Good luck Ivar

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