Electric current (ec) and Electrostatic (es) module

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I have a question regarding the differences between the Electric Current (ec) and Electrostatic (es) modules in COMSOL software. Specifically, I want to perform simulations to analyze potential, current density, and related parameters.

In the Electrostatic (es) module, I know that only the relative permittivity parameter is used for calculations, employing Poisson's and Laplace's equations. However, in the Electric Current (ec) module, both electrical conductivity and relative permittivity are used. When analyzing potential distribution, I observed that changing the conductivity value affects the potential distribution, while changing the relative permittivity does not.

The attached image shows my model, which consists of two cathode poles surrounded by a wall. When I alter the electrical conductivity of the wall, the potential distribution changes accordingly.

I am curious whether using the Electric Current (ec) module to analyze potential is accurate in COMSOL software. And does electrical conductivity affect the potential calculation formula?. If there is an impact, what formula should be used to analyze it?

Thank you for any advice



1 Reply Last Post 2024年6月3日 GMT-4 09:47
Magnus Olsson COMSOL Employee

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Posted: 3 weeks ago 2024年6月3日 GMT-4 09:47

Hi,

This section on Charge Relaxation Theory in the AC/DC Module User's Guide covers when and why to use the Electric Currents and Electrostatics interfaces: https://doc.comsol.com/6.2/docserver/#!/com.comsol.help.acdc/acdc_ug_theory.05.31.html

If you are simulating what essentially is DC current conduction, i.e. the charge relaxtion time being much smaller than the time scale of your experiment/device, then the electric potential and field distributions are indeed goverened by the electrical conductivity. However, note that the Electrostatics equation is still consistent with the your potential distribution as space charge and/or surface charge accumulates accordingly if there is a gradual or sudden spatial change in the charge relaxation time.

Best regards,

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Magnus
Hi, This section on Charge Relaxation Theory in the AC/DC Module User's Guide covers when and why to use the Electric Currents and Electrostatics interfaces: https://doc.comsol.com/6.2/docserver/#!/com.comsol.help.acdc/acdc_ug_theory.05.31.html If you are simulating what essentially is DC current conduction, i.e. the charge relaxtion time being much smaller than the time scale of your experiment/device, then the electric potential and field distributions are indeed goverened by the electrical conductivity. However, note that the Electrostatics equation is still consistent with the your potential distribution as space charge and/or surface charge accumulates accordingly if there is a gradual or sudden spatial change in the charge relaxation time. Best regards,

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