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conducting sphere in a uniform electrical field

Posted 29 giu 2021, 14:53 GMT-4 Electromagnetics, Low-Frequency Electromagnetics Version 5.6 2 Replies

HP Doctoral student, Uppsala University
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I am new to COMSOL and trying to simulate field enhancement of sphere surface when a conducting sphere is in a uniform electric field.

I used electrocstatic physics (2D) and gave +100V for left boundry and -100V for right boundry to generate an uniform field. In between these two boundaries, sphere is placed.

According to analytical solution, the value of electric field at the poles of sphere should be 3 times of uniform/background electric field. But I can not get that answer and the field enhancing factor varies with radius in my simulation. What would be the mistake?

I would really appreciate it if you can comment on this matter. Simulation is attached herewith

2 Replies Last Post 30 giu 2021, 05:32 GMT-4
Robert Koslover Certified Consultant
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Posted: 3 years ago 29 giu 2021, 15:39 GMT-4
Updated: 3 years ago 29 giu 2021, 15:41 GMT-4

As soon as I opened your model, I noticed a big problem with it. Your 2D model is a simple X-Y plane 2D model. It is NOT an axisymmetric (R-Z) 2D model. So you are not modeling a sphere at all! The circle in your model is geometrically representative of an infinite cylinder (with its axis out of the page). This is rather different, of course, than a sphere. For the latter, you need to use an axisymmetric 2D geometry. Anyway, that's as far as I checked, before writing this reply. So you should fix that major error in your model first, then see if there are any other problems to deal with. Good luck. :)

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
As soon as I opened your model, I noticed a big problem with it. Your 2D model is a simple X-Y plane 2D model. It is NOT an axisymmetric (R-Z) 2D model. So you are not modeling a sphere at all! The circle in your model is geometrically representative of an infinite *cylinder* (with its axis out of the page). This is rather different, of course, than a sphere. For the latter, you need to use an axisymmetric 2D geometry. Anyway, that's as far as I checked, before writing this reply. So you should fix that major error in your model first, *then* see if there are any other problems to deal with. Good luck. :)
HP Doctoral student, Uppsala University
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Posted: 3 years ago 30 giu 2021, 05:32 GMT-4

Dear Robert Koslover,

Thank you very much for the commect.

It works correctly.

Dear Robert Koslover, Thank you very much for the commect. It works correctly.

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