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Need help with Magnetic and Electric Fields Error

Posted May 18, 2012, 1:44 p.m. EDT Low-Frequency Electromagnetics Version 4.2a 3 Replies

Jarred Young
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Greetings,

I'm trying to generate a model with a cylindrical anode, two metallic electrodes, and two magnets with the MER Module so I can model both the E and B Fields together so I can look at ExB drift effects. However, I keep getting this same error:

Failed to find a solution.
Singular matrix.

There are 213295 void equations (empty rows in matrix) for the variable mod1.V.
at coordinates: (-0.308496,-0.261123,-0.294355), (-0.299595,-0.278459,-0.287582), (-0.289647,-0.29545,-0.280739), (-0.288168,-0.272107,-0.304823), (-0.278712,-0.28882,-0.298166), ...
and similarly for the degrees of freedom (empty columns in matrix).
Returned solution is not converged.

I've double-checked all of my material properties and I've input the electric potentials using the Initial Values, but it's still having a hard time looking for the voltage (?). I'm not sure what boundary conditions I've missed to get a singular matrix and nothing's popping out at me. Does anyone have any ideas?

Live Long and Prosper,
JAY

P.S.: I can't attach my file because the size of the file is too large.
3 Replies Last Post May 18, 2012, 4:41 p.m. EDT
Robert Koslover Certified Consultant
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Posted: 1 decade ago May 18, 2012, 2:42 p.m. EDT
Hmm. Not sure, based on the limited info. There may be a clue in your statement that you "input the electric potentials using the Initial Values." I haven't used the AC/DC module much lately, but "initial values" doesn't sound like the right place to specify electric potentials. Potentials would normally be specified as boundary conditions, not initial values, for most problems.
Hmm. Not sure, based on the limited info. There may be a clue in your statement that you "input the electric potentials using the Initial Values." I haven't used the AC/DC module much lately, but "initial values" doesn't sound like the right place to specify electric potentials. Potentials would normally be specified as boundary conditions, not initial values, for most problems.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 18, 2012, 3:47 p.m. EDT
Hi

If it's i MEF are you sure all your materials have some conductance ?
0[S/m] is not allowed, use 1 or 10 for air, even if it is not really "true"

--
Good luck
Ivar
Hi If it's i MEF are you sure all your materials have some conductance ? 0[S/m] is not allowed, use 1 or 10 for air, even if it is not really "true" -- Good luck Ivar
Jarred Young
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Posted: 1 decade ago May 18, 2012, 4:41 p.m. EDT
Ivar,

Thanks for the advice. My solution is converging now and I'm getting results that are comparable with my B-Field only model. Thank you!

Live Long and Prosper,
JAY
Ivar, Thanks for the advice. My solution is converging now and I'm getting results that are comparable with my B-Field only model. Thank you! Live Long and Prosper, JAY

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