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Small changes in size introduce a "divergence cleaning" error
Posted Apr 3, 2015, 10:53 a.m. EDT Low-Frequency Electromagnetics, Geometry Version 5.0 1 Reply
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Hi,
I'm trying to model magnetic field around a stationary uniform current density. Check the attached file.
The model is really simple: two concentric cylinders both with height "len" and the bigger one has radius "len" and smaller one has radius "len/10".
Now the bizarre thing is that when the parameter "len" is about 300 nm or higher, then everything works well. When len is less than 200 nm, I always get the "Divergence cleaning failed for linear system." error. When len is between 200 and 300, it sometimes gives the error and sometimes it doesn't.
Tweaking the external current density and conductivity didn't change the behavior.
What could cause this error? How could I fix it? I need to do similar simulations to this in length scales of about ~5 nm.
I'm trying to model magnetic field around a stationary uniform current density. Check the attached file.
The model is really simple: two concentric cylinders both with height "len" and the bigger one has radius "len" and smaller one has radius "len/10".
Now the bizarre thing is that when the parameter "len" is about 300 nm or higher, then everything works well. When len is less than 200 nm, I always get the "Divergence cleaning failed for linear system." error. When len is between 200 and 300, it sometimes gives the error and sometimes it doesn't.
Tweaking the external current density and conductivity didn't change the behavior.
What could cause this error? How could I fix it? I need to do similar simulations to this in length scales of about ~5 nm.
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1 Reply Last Post Apr 4, 2015, 12:23 p.m. EDT
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Posted:
9 years ago
Ok, apparently using the "Gauge fixing for A field" for all domains and a direct solver solves this problem. Some other options/solutions may be found here: www.comsol.com/community/forums/general/thread/16196/
But I'm still a bit confused why the error would depend on the size of the geometry like that with the default iterative solver.
But I'm still a bit confused why the error would depend on the size of the geometry like that with the default iterative solver.