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Lorentz force

Posted 25 août 2010, 09:08 UTC−4 Low-Frequency Electromagnetics 6 Replies

mb
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Hi,

with the new v4.0a, I miss the predefined Lorentz forces in the AC/DC module. In magnetic field mode (mf), there is at least the Lorentz force mf.FLtz_xyz. In magnetic and electric field mode (mef), there is no Lorentz force predefined.

I also miss time-averaged Lorentz force that was available in earlier versions.
Nevertheless, I found the time-averaged Lorentz force in "cold crucible" from the model gallery...maybe because this is translated from 3.5a??

Or did I miss anything, a hidden checkbox maybe?

Thanks
6 Replies Last Post 23 mai 2013, 07:13 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 25 août 2010, 10:18 UTC−4
Hi

I couldnt find them either, but there are still some "missings to come" mentionned in the ACDC relase notes, so it could be that 3D Lorentz forces and mef/ec expressions will be completed in the next relase

--
Good luck
Ivar
Hi I couldnt find them either, but there are still some "missings to come" mentionned in the ACDC relase notes, so it could be that 3D Lorentz forces and mef/ec expressions will be completed in the next relase -- Good luck Ivar
mb
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Posted: 1 decade ago 25 août 2010, 10:30 UTC−4
Again, thanks for your kind support!!
Again, thanks for your kind support!!
Linus Andersson COMSOL Employee

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Posted: 1 decade ago 26 août 2010, 10:53 UTC−4
Hi!

Indeed, we are working on bringing back these and other expressions, as well as introducing new ones. Feel free to send your suggestions directly to support@comsol.com, to help us prioritize our efforts.

Best regards,

Linus
Hi! Indeed, we are working on bringing back these and other expressions, as well as introducing new ones. Feel free to send your suggestions directly to support@comsol.com, to help us prioritize our efforts. Best regards, Linus
mb
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Posted: 1 decade ago 27 août 2010, 02:15 UTC−4
Hi again,

again looking at it, it seems that the (time/phase-dependent) Lorentz force has wrong units. It should be a volume force density N/m^3 more than a force in N as it comes from F_L=J x B. Copying the implemented definition to a new variable definition gives N/m^3.

Best, Marcel from rainy Berlin
Hi again, again looking at it, it seems that the (time/phase-dependent) Lorentz force has wrong units. It should be a volume force density N/m^3 more than a force in N as it comes from F_L=J x B. Copying the implemented definition to a new variable definition gives N/m^3. Best, Marcel from rainy Berlin
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 27 août 2010, 02:36 UTC−4
Hi

Yes I have also seen this one and reported it to support, they were aware about it as indeed there are still a few units errors in there, you can see it in the equations if you turn them on (as units are redefined and not calculated for internal variables). They told me that they will fix this for next release.

Actually if you calculate it out fully yourself by a volume integration using the J and B, then the units will be right, but via the internal Lorentz force FL you will have a [m] error in the units

--
Good luck
Ivar
Hi Yes I have also seen this one and reported it to support, they were aware about it as indeed there are still a few units errors in there, you can see it in the equations if you turn them on (as units are redefined and not calculated for internal variables). They told me that they will fix this for next release. Actually if you calculate it out fully yourself by a volume integration using the J and B, then the units will be right, but via the internal Lorentz force FL you will have a [m] error in the units -- Good luck Ivar
Sanjay Kumar Bagaria
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Posted: 1 decade ago 23 mai 2013, 07:13 UTC−4
Hi,

Can you please let me know in which version(s) of comsol can I find the predefined lorentz force options in AC/DC module. Is it possible to do it using Version 3.3a

Thanks
Hi, Can you please let me know in which version(s) of comsol can I find the predefined lorentz force options in AC/DC module. Is it possible to do it using Version 3.3a Thanks

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