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setting up "air" enviroment

Posted 15 mars 2012, 11:44 UTC−4 Geometry Version 4.2 5 Replies

Ted Zhang
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Hi,
I am trying to do some electrostatic study, for example, there are 2 metal block sitting on a SiO2 substrate, I want to study the electrical field between the metal blocks. so I use a work plane to represent the SiO2, then extrude, then start 2nd work plane on the top surface of SiO2, put 2 rectangles for the 2 metal blocks. and finally draw a sphere to enclose the earlier structure, and make the interior of the sphere full of air to let the whole structure sitting in air, I am not sure if I built the structure correctly because the results is kind of odd. then I tried 2nd way, this time I draw the sphere first, then try to insert a work plane inside to build my SiO2. however, COMSOL would not let me to put an work plane inside the sphere. I wonder what is the right way to build the structure.

please read the update post below.

regards,
5 Replies Last Post 15 mars 2012, 19:35 UTC−4
Ted Zhang
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Posted: 1 decade ago 15 mars 2012, 13:10 UTC−4
HI,
now I know whey the results from my first plot looks odd. in that plot, I enclosed the whole structure with an "air" sphere at the end. so when you draw the results in "volume" mode("plot 1" in attached file) , it will only show the outside air sphere's potential, which should be or very close to be an equal potential volume. then it appears the same color. Even if I turn on "transparency" option, COMSOL still can not show the inside metal electrode's potential correctly; you only see a green color sphere. but if you choose "slice" mode and cut a plane out of the structure, it do show the potential difference. I attached the model file. then my questions is : Is there a better way to show the inside structure potential clearly besides using"slice" mode?

regards,
HI, now I know whey the results from my first plot looks odd. in that plot, I enclosed the whole structure with an "air" sphere at the end. so when you draw the results in "volume" mode("plot 1" in attached file) , it will only show the outside air sphere's potential, which should be or very close to be an equal potential volume. then it appears the same color. Even if I turn on "transparency" option, COMSOL still can not show the inside metal electrode's potential correctly; you only see a green color sphere. but if you choose "slice" mode and cut a plane out of the structure, it do show the potential difference. I attached the model file. then my questions is : Is there a better way to show the inside structure potential clearly besides using"slice" mode? regards,

Attachments:

Alexander Kuznetsov
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Posted: 1 decade ago 15 mars 2012, 14:41 UTC−4
In Results-Data Sets, create new solution (Solution 2). Add Selection property to Solution 2 and choose domains 2-4 (all domains except the sphere). Now in your plot, change Data set from Solution 1 to Solution 2.

By the way, instead of working with Work Plane you should use Blocks to build your structure. Also instead of using huge air sphere around you could use much small rectangular block of air.
In Results-Data Sets, create new solution (Solution 2). Add Selection property to Solution 2 and choose domains 2-4 (all domains except the sphere). Now in your plot, change Data set from Solution 1 to Solution 2. By the way, instead of working with Work Plane you should use Blocks to build your structure. Also instead of using huge air sphere around you could use much small rectangular block of air.
Ted Zhang
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Posted: 1 decade ago 15 mars 2012, 16:48 UTC−4
Hi, Alexander,
I followed your suggestion, the problem is solved. thanks.
when you said " use Blocks instead of work plane" , I guess it is because this specific structure here is easier to build with blocks, isn't it? then but back to my 2nd way to build this structure: starting with a sphere, then trying to draw a work-plane inside, which is failed. The reason I failed is because COMSOL would not allow drawing work-plane inside blocks, is it?

regards,
Hi, Alexander, I followed your suggestion, the problem is solved. thanks. when you said " use Blocks instead of work plane" , I guess it is because this specific structure here is easier to build with blocks, isn't it? then but back to my 2nd way to build this structure: starting with a sphere, then trying to draw a work-plane inside, which is failed. The reason I failed is because COMSOL would not allow drawing work-plane inside blocks, is it? regards,
Alexander Kuznetsov
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Posted: 1 decade ago 15 mars 2012, 18:07 UTC−4
I'm not sure why you failed by you can define work planes everywhere.
In general, I avoid using work planes for the structure I can do using 3d shapes.
I'm not sure why you failed by you can define work planes everywhere. In general, I avoid using work planes for the structure I can do using 3d shapes.
Ted Zhang
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Posted: 1 decade ago 15 mars 2012, 19:35 UTC−4
Hi, Alexander,
actually it worked this time. I must mess something up earlier.

regards,
Hi, Alexander, actually it worked this time. I must mess something up earlier. regards,

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