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time dependent capacitance

Posted Jun 1, 2015, 12:38 p.m. EDT Low-Frequency Electromagnetics, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.4, Version 5.2a 4 Replies

Syarif Husein
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Dear all

I am new in COMSOL. I have a few questions related to the capacitance.
1. How to compute capacitance in time dependent study ? I couldn’t find any capacitance in the postprocessing menu in COMSOL 4.4.
2. What is the equation that comsol use to compute the capacitance value? I mean what is the physics equation behind it?
3. I read that COMSOL solve the governing equations with finite element method. what kind of
finite element used by COMSOL to solve the equation? anyone know some userguides that I can learn about the computation technique?

Best regards,
Syarif
4 Replies Last Post Aug 3, 2017, 7:58 a.m. EDT
Levin Dieterle
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Posted: 10 years ago Jun 2, 2015, 7:12 a.m. EDT
Dear Syarif,

that depends on the used interface (electrostatic/electric currents) whether you get the capacitance or the admittance. You need a terminal instead of an applied potential to get these values as variable.

Kind regards,
Levin
Dear Syarif, that depends on the used interface (electrostatic/electric currents) whether you get the capacitance or the admittance. You need a terminal instead of an applied potential to get these values as variable. Kind regards, Levin
Syarif Husein
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Posted: 10 years ago Jun 2, 2015, 10:31 a.m. EDT
Dear Levin.

Yes, I used electrostatic module and defined two terminals -time dependent voltage value for the first terminal, and zero voltage for the second terminal- as the boundary settings to compute the capacitance.
In "stationary" study I could find the capacitance menu when I used constant voltage, but couldn't find the capacitance menu when "time dependent" study is applied. I used time dependent voltage for time dependent study. So how to compute this capacitance in time dependent study? or may be you know another technique to compute this capacitance.

Best regards,
Syarif
Dear Levin. Yes, I used electrostatic module and defined two terminals -time dependent voltage value for the first terminal, and zero voltage for the second terminal- as the boundary settings to compute the capacitance. In "stationary" study I could find the capacitance menu when I used constant voltage, but couldn't find the capacitance menu when "time dependent" study is applied. I used time dependent voltage for time dependent study. So how to compute this capacitance in time dependent study? or may be you know another technique to compute this capacitance. Best regards, Syarif
Suketu Naik
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Posted: 7 years ago Aug 3, 2017, 7:36 a.m. EDT
Syarif/anyone else,
did anyone figure out how to do this?
Any help will be greatly appreciated.
I have tried the following:
under Electrostatics->terminal->Sinu(t)
I define Sinu as a sinusoidal voltage source at the desired frequency.
When I run the study, the output shows no results.
Syarif/anyone else, did anyone figure out how to do this? Any help will be greatly appreciated. I have tried the following: under Electrostatics->terminal->Sinu(t) I define Sinu as a sinusoidal voltage source at the desired frequency. When I run the study, the output shows no results.
Suketu Naik
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Posted: 7 years ago Aug 3, 2017, 7:58 a.m. EDT
never mind, I figured it out. I had to delete the study all together and add a new time-dependent study. I also played with DC value (nonzero). Hope that helps someone...
never mind, I figured it out. I had to delete the study all together and add a new time-dependent study. I also played with DC value (nonzero). Hope that helps someone...

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