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Computations in void

Posted 19 mai 2020, 05:18 UTC−4 Electromagnetics, General Version 5.4 3 Replies

Иван Иванович Иванов
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Hi!

I'm junior in COMSOL and try to compute electrical potential of electrodes between these electrodes on cross-plane in vacuum chamber. Vacuum in this chamber is very high. The question is how to compute potetial between two cylinders? Did I need to create a some space (sphere around electrodes for example) with air material with low pressure and then compute and then plot on needed plane? If I try to plot without surrounding air sphere COMSOL says that plot is empty. If I create a sphere, then COMSOL creates a lot of unnecessary mesh elemets and computation time is greatly increasing.

Thanks!

3 Replies Last Post 19 mai 2020, 07:30 UTC−4
Edgar J. Kaiser Certified Consultant
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Posted: 5 years ago 19 mai 2020, 06:25 UTC−4

Ivan,

the void is not empty in electromagnetics, there are the fields. You need to mesh the space if you want to use a finite element method. If your problem is purely electrostatic, without currents and magnetic fields you might consider to use the Electrostatics, Boundary Elements interface. This avoids to mesh the void, but increases mesh expenses on the boundaries.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Ivan, the void is not empty in electromagnetics, there are the fields. You need to mesh the space if you want to use a finite element method. If your problem is purely electrostatic, without currents and magnetic fields you might consider to use the Electrostatics, Boundary Elements interface. This avoids to mesh the void, but increases mesh expenses on the boundaries. Cheers Edgar
Иван Иванович Иванов
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Posted: 5 years ago 19 mai 2020, 07:00 UTC−4
Updated: 5 years ago 19 mai 2020, 07:05 UTC−4

Thank you for answering me, Edgar.

the void is not empty in electromagnetics, there are the fields.

Did you mean that there is no need to fill the empty space in COMSOL?

you might consider to use the Electrostatics

Yes, I use Electrostatics. But when I try to create a plot in plane between electrodes, which placed in some distance one from another, COMSOL warnings me about empty plot. I created a Cut Plane in Data Sets between electrodes to extract data, but there is no data. Can I indicate that the surrounding space (in sone planes) should participate in the calculations?

Thank you for answering me, Edgar. >the void is not empty in electromagnetics, there are the fields. Did you mean that there is no need to fill the empty space in COMSOL? >you might consider to use the Electrostatics Yes, I use Electrostatics. But when I try to create a plot in plane between electrodes, which placed in some distance one from another, COMSOL warnings me about empty plot. I created a Cut Plane in Data Sets between electrodes to extract data, but there is no data. Can I indicate that the surrounding space (in sone planes) should participate in the calculations?
Edgar J. Kaiser Certified Consultant
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Posted: 5 years ago 19 mai 2020, 07:30 UTC−4

No exactly the opposite. In FEM you must mesh the void. In BEM this is not needed.

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
No exactly the opposite. In FEM you must mesh the void. In BEM this is not needed.

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