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Electrical potential distribution in electrostatics

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I'm going to simulate a multiple-layer structure with charge induction after friction. The material of the central domain is aluminum in which surface charge density of its top and bottom surfaces are set to be 1.14*10e-4 C/m2. And materials of the arch-shaped domains are respectively PDMS (a polymer) and aluminum from inside to outside. So I defined the surface charge density of the bottom surface of upper PDMS and top surface of lower PDMS to be -1.3*10e-4 C/m2.

But I can't obtain the expected electrical potential distribution just like the figure shows. The central domain of the expected figure shows a well-distributed electrical potential instead of almost zero even negative electrical potential in my simulation.

So is there anyone give me some hints for that problem?I personally guess that may be I forgot add some necessary boundaries. But I really has no clue. Thanks in advance.



2 Replies Last Post Jul 22, 2016, 5:05 a.m. EDT

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Posted: 8 years ago Jul 20, 2016, 12:57 p.m. EDT
I've found that the solution given by COMSOL is usually correct given how I've formulated the problem. If I'm confused, what I usually do is to simplify the geometry and boundaries so that the solution is obvious from basic physics. That generally causes me to see my formulation mistake.

By the way, in this case, since you're questioning positive and negative, I'm curious where/how did you define ground?
I've found that the solution given by COMSOL is usually correct given how I've formulated the problem. If I'm confused, what I usually do is to simplify the geometry and boundaries so that the solution is obvious from basic physics. That generally causes me to see my formulation mistake. By the way, in this case, since you're questioning positive and negative, I'm curious where/how did you define ground?

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Posted: 8 years ago Jul 22, 2016, 5:05 a.m. EDT
Hi Chris

Thank you very much for your reply. I'll try a much simpler geometry to see if it works.

Actually, I didn't define ground. All boundaries that I defined are Charge Conservation, Zero Charge, Initial Values, Electric Potential (set zero), Surface charge density of boundaries. Does the ground will affect the simulation result? If it does, which boundary should I set for the ground?

Best regards
Hi Chris Thank you very much for your reply. I'll try a much simpler geometry to see if it works. Actually, I didn't define ground. All boundaries that I defined are Charge Conservation, Zero Charge, Initial Values, Electric Potential (set zero), Surface charge density of boundaries. Does the ground will affect the simulation result? If it does, which boundary should I set for the ground? Best regards

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