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boundary settings- Thin layer (surface thickness)

Posted May 11, 2012, 3:28 p.m. EDT Low-Frequency Electromagnetics, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.2, Version 4.2a 3 Replies

Bahar
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Hello everyone

I have a question about settings for boundary conditions. In most of physics, when you use 3d and you want to define a boundary condition like dielectric shielding for one surface there is one option called "Thin layer".
For this "Thine layer" you should define "Surface thickness" which is by default 1m.
My question is that what exactly this surface thickness means? because it seems it can affect my results a lot.
I know it is not thickness of my domain (if the domain is a cube with dimension of 0.1 um). So what exactly is this? I went through some tutorials and i couldn't find any explanation.

Best
Bahar

3 Replies Last Post May 18, 2012, 11:46 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 12, 2012, 12:40 p.m. EDT
Hi Bahar

Well I'm not a ES specialist (I do not like that one as the current is not flowing so I get it often all wrong, I prefer think in terms of EC with currents, again just a habit from my electromechanical studies ;)
But the Thin Layer thickness is the thickness of the layer you add on the boundary (outside of your domain), now it's not necesarily to be compared with your dimensions but rather to the propagation length of your EM field or wave.

What I often do to learn more about the COMSOL's equations, is to replace such numerical input fields with a "my_sd" variable name (even if not defined) and then look into the "equation view" to find it there (es.ds in your case) and to see where it is used and what COMSOL is doing with it in the other equations

--
Good luck
Ivar
Hi Bahar Well I'm not a ES specialist (I do not like that one as the current is not flowing so I get it often all wrong, I prefer think in terms of EC with currents, again just a habit from my electromechanical studies ;) But the Thin Layer thickness is the thickness of the layer you add on the boundary (outside of your domain), now it's not necesarily to be compared with your dimensions but rather to the propagation length of your EM field or wave. What I often do to learn more about the COMSOL's equations, is to replace such numerical input fields with a "my_sd" variable name (even if not defined) and then look into the "equation view" to find it there (es.ds in your case) and to see where it is used and what COMSOL is doing with it in the other equations -- Good luck Ivar
Bahar
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Posted: 1 decade ago May 12, 2012, 1:32 p.m. EDT
Interesting!! Now i have an idea bout this.
And thanks a lot for telling me about the way you handle Comsol equations. I, sometimes, get really confused about how Comsol use some parameters. I think by following your advice i can get a deeper understanding about this.
Thanks a lot for your reply

Best
Bahar
Interesting!! Now i have an idea bout this. And thanks a lot for telling me about the way you handle Comsol equations. I, sometimes, get really confused about how Comsol use some parameters. I think by following your advice i can get a deeper understanding about this. Thanks a lot for your reply Best Bahar
SOhan
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Posted: 1 decade ago May 18, 2012, 11:46 a.m. EDT
This allow users to model a thin film of shield overed on the domain without even creating domain and discretization. Here the amterial thickness should not be more than 5 times of the skin depth for given EM frequency
This allow users to model a thin film of shield overed on the domain without even creating domain and discretization. Here the amterial thickness should not be more than 5 times of the skin depth for given EM frequency

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