Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Cube in a cube

Please login with a confirmed email address before reporting spam

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 2010年8月4日 GMT-4 15:24
Magnus Ringh COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2010年8月4日 GMT-4 02:21
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)

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2010年8月4日 GMT-4 03:07
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

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2010年8月4日 GMT-4 15:24
Thank you very much everyone.
Thank you very much everyone.

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2010年8月4日 GMT-4 15:24
Thank you very much.
Thank you very much.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.