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.

What is the Difference: Maxwell Stress Tensor vs Lorentz Force Integration

Please login with a confirmed email address before reporting spam

I am working on a simulation of a Linear Induction Motor.

With the Magnetic Fields Module, there is the Force Calculation Feature. There are two ways to read from the Force Calculation Feature: You can add an Integration Feature and integrate: intop1(mf.FLtzx) for example for the Thrust Force in my case. Or you can just read from the expression: mf.Forcex_motor for example. (This method uses the Maxwell Stress Tensor.)

However, I get different outcomes from both expressions. Why is this?


1 Reply Last Post 21.02.2024, 06:00 GMT-5
Magnus Olsson COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 9 months ago 21.02.2024, 06:00 GMT-5
Updated: 9 months ago 21.02.2024, 06:00 GMT-5

Dear Joseph,

The first method you mention is to integrate the Lorentz force, that is JxB. This does not account for any induced magnetization so it can only be used to compute forces on non-magnetic, current-carrying objects. The second method (Maxwell Stress Tensor) is general so if a magnetic core is involved, that is what you should use.

Best regards,

-------------------
Magnus
Dear Joseph, The first method you mention is to integrate the Lorentz force, that is **J**x**B**. This does not account for any induced magnetization so it can only be used to compute forces on non-magnetic, current-carrying objects. The second method (Maxwell Stress Tensor) is general so if a magnetic core is involved, that is what you should use. 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.