Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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.

Calculating EM Force in the Electromagnetic Waves (emw) Environment

Hi,

This should be a very straightforward question. I would like to calculate the time-averaged electromagnetic force (via integrating the Maxwell Stress tensor over a surface). The fields that I need are taken from the Electromagnetic Waves (emw) physics environment. There is no node available for "Force Calculation", as there is in some of the AC/DC environments. However, I do see that I can perform surface integrations in post-processing and that I have access to the z-component, etc., of the Maxwell Stress Tensor. However, this is confusing to me, since there are only 3 components available and there should be 9 components of the Maxwell Stress Tensor (it's a 3x3 matrix). Moreover, I was wondering if the integration is considering the surface normal of the surface of interest. I am interested in doing this for both a 3D case and a 2D axially-symmetric case.

So then, two main questions:

1) Why are there only 3 components available for the Maxwell Stress Tensor?
2) I would like to calculate the force using the Electromagnetic Waves (emw) environment. Can I do this?

Thanks for your help,
Brian

1 Reply Last Post Jun 14, 2014, 2:11 AM EDT
COMSOL Moderator

Hello Brian Tierney

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Posted: 3 years ago Jun 14, 2014, 2:11 AM EDT
Hi Brian
I have the same question with you .
I just want to know how to to calculate the force in the RF module.
Do you have any suggestions?

Best regards!
Hi Brian I have the same question with you . I just want to know how to to calculate the force in the RF module. Do you have any suggestions? Best regards!

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.