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Max/Min Electric Field Point

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Hi

I am performing 2d axisymmetric electric field simulations and noticed a problem finding the maximum electric field in my results.

By using the max/min surface option I get 5.81 which is located at r = 9.899999999999999 and z = 0.

However, if I evaluate the electric field using these exact coordinates I will get a different value, in this case for r = 9.899999999999999 and z = 0, the value reduces to 5.63.

Likewise, if I cut 2d or 3d lines and evaluate the maximum point in them I will get different results.

Please see the image attached.

Thanks



1 Reply Last Post Jun 17, 2022, 10:41 a.m. EDT
Robert Koslover Certified Consultant

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Posted: 2 years ago Jun 17, 2022, 10:41 a.m. EDT

I didn't look at your figures, but from your description, it sounds like you are evaluating these values by different means. Remember, the finite element representation is discrete. Max/Min are based on computations variously using/interpolating the values in the elements around the point of interest. The differences you see give you an idea of how much numerical error is involved in your particular combination of physics, geometry, mesh, etc.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
I didn't look at your figures, but from your description, it sounds like you are evaluating these values by different means. Remember, the finite element representation is *discrete*. Max/Min are based on computations variously using/interpolating the values in the elements around the point of interest. The differences you see give you an idea of how much numerical error is involved in your particular combination of physics, geometry, mesh, etc.

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