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Iterative solver and gauge fixing

Posted 30 mars 2011, 13:30 UTC−4 Low-Frequency Electromagnetics, Studies & Solvers Version 3.5a, Version 4.1 4 Replies

Dmitry Lazutkin
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Dear Colleagues,

I sincerely hope you are all doing fine. Could you be so kind to advise me on the following issue, please?

The problem I have is quite an ordinary induction current problem in 3D with a stranded conductor of almost zero conductivity. I have managed to get a great solution with COMSOL, while enforcing the gauge fixing and using the direct solver. But when I am changing the solver to iterative one (due to fine mesh for example), I am not able to get a solution anymore, even with the Vanka preconditioner -- it keeps saying me that there are zeros on the diagonal of a submatrix needed for the SSOR update in the Vanka algorithm. Could you be so kind to help me with it, please?

Thank you very very much for your help, and have a beautiful day!

With best wishes,

Dima
4 Replies Last Post 1 déc. 2014, 06:04 UTC−5
COMSOL Moderator

Hello Dmitry Lazutkin

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Julien Givernaud
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Posted: 10 years ago 28 nov. 2014, 04:59 UTC−5
Hello,

old post but problem still active
Someone knows which configuration of iterative solver to use with 3D Gauge fixing A field?J

Regards
Hello, old post but problem still active Someone knows which configuration of iterative solver to use with 3D Gauge fixing A field?J Regards
Jens Krause
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Posted: 10 years ago 1 déc. 2014, 02:20 UTC−5
Hi,

I use the GMRES Solver with Vanka-preconditioner and the "divergence condition variable" as the Vanka variable.

Alternativly you can omit gauge fixing and the "SOR Gauge" preconditioner.

Regards

jens
Hi, I use the GMRES Solver with Vanka-preconditioner and the "divergence condition variable" as the Vanka variable. Alternativly you can omit gauge fixing and the "SOR Gauge" preconditioner. Regards jens
Julien Givernaud
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Posted: 10 years ago 1 déc. 2014, 03:43 UTC−5
Thank you for your answer.
You use the default solver which is created when adding a gauge fixing for the A field in mef physic.
I have to use this Gauge otherwise electric potential is wrong in the model. I don't find the "SOR Gauge" preconditionner that you talk about.
I have tried simple cases in 3D, it works the the default solver but the convergence is very mesh dependent. With a finer mesh, no convergence! If I had some "impedance boundary condition" on conductive surfaces, no convergence anymore....
I join a simple model in 3D, if someone knows how to make it converges...

Regards
Thank you for your answer. You use the default solver which is created when adding a gauge fixing for the A field in mef physic. I have to use this Gauge otherwise electric potential is wrong in the model. I don't find the "SOR Gauge" preconditionner that you talk about. I have tried simple cases in 3D, it works the the default solver but the convergence is very mesh dependent. With a finer mesh, no convergence! If I had some "impedance boundary condition" on conductive surfaces, no convergence anymore.... I join a simple model in 3D, if someone knows how to make it converges... Regards

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Julien Givernaud
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Posted: 10 years ago 1 déc. 2014, 06:04 UTC−5
The model joined is on Comsol 5.0
The model joined is on Comsol 5.0

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