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AC/DC model: Matrix has zero on diagonal.

Posted 14.02.2011, 08:48 GMT-5 Low-Frequency Electromagnetics Version 4.1 4 Replies

Massimo Bechis
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Hi everybody.
I have to calculate the magnetic field around three cables.
The model I built simply includes the three straight conductors and air around them.
A small voltage difference is applied and the Electric Currents module is first run to compute the current flowing in each conductor.

After that I run the Magnetic Felds module, but Comsol returns the following error message:

"Failed to find a solution.
Matrix has zero on diagonal.
Returned solution has not converged."

I'v done many attempts to solve the problem changing the mesh, the way model geometry is built, and even the type of solver, without success.
Could anyone suggest aternative approaches?

Thanks

Massimo
4 Replies Last Post 20.05.2013, 04:31 GMT-4
COMSOL Moderator

Hello Massimo Bechis

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Chatra Prisandi
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Posted: 1 decade ago 19.04.2011, 13:59 GMT-4
I have this problem too.. Please help us to solve this error.
What part that we have to check and revise?

Regards,

Chatra
I have this problem too.. Please help us to solve this error. What part that we have to check and revise? Regards, Chatra
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 23.04.2011, 08:23 GMT-4
Hi

why are you using those two physics, first of all the result from EC in your case is a constant current flow that you could easily enter directly into he MF, no need for the EC.

And if you really want to solve for both V and A, then use the MEF physics

There are some similar application names in 3.5

--
Good luck
Ivar
Hi why are you using those two physics, first of all the result from EC in your case is a constant current flow that you could easily enter directly into he MF, no need for the EC. And if you really want to solve for both V and A, then use the MEF physics There are some similar application names in 3.5 -- Good luck Ivar
Mladen Zec
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Posted: 1 decade ago 29.11.2011, 09:29 GMT-5
Hello,

you can just change the conductivity of the air domain to some small finite value compared to the used copper.

Best regards,
Mladen
Hello, you can just change the conductivity of the air domain to some small finite value compared to the used copper. Best regards, Mladen
saiwing bin
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Posted: 1 decade ago 20.05.2013, 04:31 GMT-4
this method really works
this method really works

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