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Cube in a cube

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hI

I'm trying to solve the problem of having a cube silicon in a cube of air.

One side of the silicon has 5Volts on it.

I chose electric current from the physics menu and assigned electric potential by right clicking on the electric current physics category.

The cube of air has 0.5m sides, the silicon has 0.1m sides.

It seems like a really simple problem but I keep getting the error messsage saying that it is a 'singular matrix'

I tried lowering the tolerance from union, from 10^-6 to 10^-15.

Also tried changing the mesh size from extremely fine to coarse.

Any help would be appeciated.


4 Replies Last Post 4 ago 2010, 15:24 GMT-4
Magnus Ringh COMSOL Employee

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Posted: 1 decade ago 4 ago 2010, 02:21 GMT-4
Hi,

The problem is in the material properties for the air domain: the elecrtic conductivity is identically 0. Changing it to a very small but nonzero number should make it possible to solve the problem quickly.

Best regards,

Magnus Ringh
COMSOL
Hi, The problem is in the material properties for the air domain: the elecrtic conductivity is identically 0. Changing it to a very small but nonzero number should make it possible to solve the problem quickly. Best regards, Magnus Ringh COMSOL

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 4 ago 2010, 03:07 GMT-4
hi

well magnus was faster than me ;)

I would also suggest to define a gnd potential somewhere, it makes more sens

so current ec means conductivity <> 0 too

--
Good luck
Ivar
hi well magnus was faster than me ;) I would also suggest to define a gnd potential somewhere, it makes more sens so current ec means conductivity 0 too -- Good luck Ivar

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Posted: 1 decade ago 4 ago 2010, 15:24 GMT-4
Thank you very much everyone.
Thank you very much everyone.

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Posted: 1 decade ago 4 ago 2010, 15:24 GMT-4
Thank you very much.
Thank you very much.

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