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electrostatics force

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I am going to find the electrostatic force between the two vertical rods with positive and negative potential and the horizental substrat with no no potential, but the value comes out is zero, i dont know why this happens?



2 Replies Last Post 2023年3月27日 GMT-4 09:06
Robert Koslover Certified Consultant

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Posted: 1 year ago 2023年3月26日 GMT-4 22:28

Sounds like you have one or more errors in your setup and specification of the problem. I encourage you to post your .mph file to the forum so that others can examine it and offer their suggestions.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
Sounds like you have one or more errors in your setup and specification of the problem. I encourage you to post your .mph file to the forum so that others can examine it and offer their suggestions.

Jeff Hiller COMSOL Employee

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Posted: 1 year ago 2023年3月27日 GMT-4 09:06
Updated: 1 year ago 2023年3月27日 GMT-4 09:12

Hello Mohsin,

Your screenshot suggests that you have drawn the conductors and not the dielectric medium. In a typical electrostatic analysis, you are solving the equation for electrostatics in the dielectric, so it is the dielectric medium that make up the geometry with the boundaries of the conductors being used to apply boundary conditions (The inside of the conductors are removed from geometry entirely unless they are needed for some other physics). A good introductor tutorial in that area is this model.

Note also that if the "rods" are cylindrical, you can't get away with a 2D model.

Best regards,

Jeff

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Jeff Hiller
Hello Mohsin, Your screenshot suggests that you have drawn the conductors and not the dielectric medium. In a typical electrostatic analysis, you are solving the equation for electrostatics in the dielectric, so it is the dielectric medium that make up the geometry with the boundaries of the conductors being used to apply boundary conditions (The inside of the conductors are removed from geometry entirely unless they are needed for some other physics). A good introductor tutorial in that area is [this model](https://www.comsol.com/model/tunable-mems-capacitor-123). Note also that if the "rods" are cylindrical, you can't get away with a 2D model. Best regards, Jeff

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