Menu

Discussion Forum

New Discussion
Filtrer

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Integrate an Isosurface

Posted 23 mars 2016, 12:54 UTC−4 Geometry, Materials, Results & Visualization Version 5.1 4 Replies

David Reens
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hello,

I am wondering if there is any way to find the area of an isosurface, or integrate a function over such a surface.

For example, if I am working with electrostatics, is there a way to check the area of the surface where es.V is equal to 100 V?

One technique I can think of would be to actually perform a volume integral of the divergence of a vector field over the volume enclosed by the surface. I can integrate over the right domain using boolean functions, and if the vector field were chosen to be orthogonal to the surface of interest, the desired area would follow by Stoke's Theorem. However, I suspect the divergence calculation would be very noisy and not yield a nice result.

I've done similar things in MATLAB, and there I found that a much more accurate technique was to export the graphics data from a plotted isosurface and sum up the areas of the tiny triangles composing the surface individually. I know I can plot and color isosurfaces in COMSOL, so could I get the area this way somehow?
4 Replies Last Post 22 nov. 2016, 14:19 UTC−5
David Reens
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 23 mars 2016, 13:05 UTC−4
If anyone is curious,

I am modeling an electro-magneto-static trap for neutral ground state molecules. The molecules are attracted to regions of low electric or magnetic fields, and so it is possible to use these fields to levitate or trap them in a vacuum chamber.

The molecules can escape the trap if they pass through a surface where the electric and the magnetic fields are exactly orthogonal, due to a process related to angular momentum transfer to the molecule's internal electron orbit.

I want to use COMSOL to plot the surface where E.B=0 and measure the area of the relevant loss region, weighted by a function of the magnitudes of the fields that describes the efficiency of the momentum transfer, and also weighted by a factor accounting for how many molecules are in which part of the trap.
If anyone is curious, I am modeling an electro-magneto-static trap for neutral ground state molecules. The molecules are attracted to regions of low electric or magnetic fields, and so it is possible to use these fields to levitate or trap them in a vacuum chamber. The molecules can escape the trap if they pass through a surface where the electric and the magnetic fields are exactly orthogonal, due to a process related to angular momentum transfer to the molecule's internal electron orbit. I want to use COMSOL to plot the surface where E.B=0 and measure the area of the relevant loss region, weighted by a function of the magnitudes of the fields that describes the efficiency of the momentum transfer, and also weighted by a factor accounting for how many molecules are in which part of the trap.
Jeff Hiller COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 23 mars 2016, 15:40 UTC−4
Hi David,
There's an easier way. Create an dataset of the Isosurface type that corresponds to V=100[V], and then under Derived Values, do a surface integration of 1 on that dataset.
Best,
Jeff
Hi David, There's an easier way. Create an dataset of the Isosurface type that corresponds to V=100[V], and then under Derived Values, do a surface integration of 1 on that dataset. Best, Jeff
David Reens
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 23 mars 2016, 16:20 UTC−4
Wonderful, Thank you Jeff!

I hadn't noticed the isosurface data set before.

Thanks again,
Dave
Wonderful, Thank you Jeff! I hadn't noticed the isosurface data set before. Thanks again, Dave
Gabriel Neves
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 8 years ago 22 nov. 2016, 14:19 UTC−5
Hi,
I have a similar problem. I'm trying to calculate the area of a Surface Plot which is in a data range (coloured area in attached image). The plot is an electric field distribution.
How can I solve my problem?
Thanks.
Hi, I have a similar problem. I'm trying to calculate the area of a Surface Plot which is in a data range (coloured area in attached image). The plot is an electric field distribution. How can I solve my problem? Thanks.

Attachments:

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content