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Plotting Current

Posted 26.07.2011, 16:02 GMT-4 Materials, Results & Visualization Version 3.5a 6 Replies

Bahar
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I have a system consisting of 2 electrodes in a box. I selected the medium in the box (on top of the electrodes) as Water. Now I want to plot the electric filed and the current between and above the electrodes.
The electric field can be plot by Cross-section plot, but there is no option about plotting the current.
Is there any special methods for plotting current in any system in Comsol?
I'm working with 3.5a Version
6 Replies Last Post 18.05.2017, 14:50 GMT-4
David Lee
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Posted: 1 decade ago 27.07.2011, 02:43 GMT-4

I have a system consisting of 2 electrodes in a box. I selected the medium in the box (on top of the electrodes) as Water. Now I want to plot the electric filed and the current between and above the electrodes.
The electric field can be plot by Cross-section plot, but there is no option about plotting the current.
Is there any special methods for plotting current in any system in Comsol?
I'm working with 3.5a Version


Hi there,

To plot current, you got to set up a subdomain integration variable which integrate the current density over all simulated domains.

To do so, you may go to Options\Integration Coupling Variables\Subdomain Variables. Remember to find out the built-in expression for current density.

All the best,

David
[QUOTE] I have a system consisting of 2 electrodes in a box. I selected the medium in the box (on top of the electrodes) as Water. Now I want to plot the electric filed and the current between and above the electrodes. The electric field can be plot by Cross-section plot, but there is no option about plotting the current. Is there any special methods for plotting current in any system in Comsol? I'm working with 3.5a Version [/QUOTE] Hi there, To plot current, you got to set up a subdomain integration variable which integrate the current density over all simulated domains. To do so, you may go to Options\Integration Coupling Variables\Subdomain Variables. Remember to find out the built-in expression for current density. All the best, David
Bahar
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Posted: 1 decade ago 27.07.2011, 12:34 GMT-4
Dear David

Thanks a lot for your reply.
I can not understand this part of your answer:
"Remember to find out the built-in expression for current density."

should I define some special expression for Current density by myself? I mean by special formula or number?

Dear David Thanks a lot for your reply. I can not understand this part of your answer: "Remember to find out the built-in expression for current density." should I define some special expression for Current density by myself? I mean by special formula or number?
Bahar
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Posted: 1 decade ago 27.07.2011, 12:42 GMT-4
In order to describe the problem more accurately , I can say I am re-simulating one of the Comsol examples "Capacitive 3D comb drive" which is available on line.
Now, in this system, I want to plot the current
In order to describe the problem more accurately , I can say I am re-simulating one of the Comsol examples "Capacitive 3D comb drive" which is available on line. Now, in this system, I want to plot the current
David Lee
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Posted: 1 decade ago 27.07.2011, 22:47 GMT-4
Hi there,

The expression for current density is already generated as an build-in parameter which you can refer to the user's guide to find out the exact form. It could be like normJ_emdc. Try to read user's guide or Google it.

All the best,

David
Hi there, The expression for current density is already generated as an build-in parameter which you can refer to the user's guide to find out the exact form. It could be like normJ_emdc. Try to read user's guide or Google it. All the best, David
Bahar
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Posted: 1 decade ago 28.07.2011, 11:01 GMT-4
Dear David. Thanks a lot for your great help
I also find another way to solve this problem but I am not sure if it's correct or not. I would appreciate if you could comment on this.
Before this, I simulated the system I explained in MEMS MODULE--->ELECTROSTATICS
then yesterday, I change this and simulate the system in ELECTROMAGNETIC--->CONDUCTIVE MEDIA DC
now in this mode, I can plot the current density directly in the program.
I have saw systems similar to mine which were simulated in both of these modes so I am not sure which one is correct.

Moreover, when I do the integration it will only give me a number as a final result. I can not draw a plot with this integration technique, Is that right? or may be I am missing something.

I appreciate your kind help and Reply David
Dear David. Thanks a lot for your great help I also find another way to solve this problem but I am not sure if it's correct or not. I would appreciate if you could comment on this. Before this, I simulated the system I explained in MEMS MODULE--->ELECTROSTATICS then yesterday, I change this and simulate the system in ELECTROMAGNETIC--->CONDUCTIVE MEDIA DC now in this mode, I can plot the current density directly in the program. I have saw systems similar to mine which were simulated in both of these modes so I am not sure which one is correct. Moreover, when I do the integration it will only give me a number as a final result. I can not draw a plot with this integration technique, Is that right? or may be I am missing something. I appreciate your kind help and Reply David
Abhinav Kalkhanda
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Posted: 8 years ago 18.05.2017, 14:50 GMT-4
Updated: 8 years ago 18.05.2017, 14:50 GMT-4
Hi david
I am using 5.2a. Where exactly is the option for Options\Integration Coupling Variables\Subdomain Variables located in comsol.
Hi david I am using 5.2a. Where exactly is the option for Options\Integration Coupling Variables\Subdomain Variables located in comsol.

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