# Need help with Maxwell magnetic simulation

1. Jan 24, 2013

### shuhart

Hello, I am a student from Germany and I stared my first project using ANSOFT Maxwell.

I have read several tutorials and have a few questions how to simulate my problem. Hope I can find some help here.

First my problem:

I have two identical magnetic disks. These disks are so positioned that the y-axis is the symmetric axis of the problem.
Both disks are rotating with same speed and direction. I want to simulate the magnetic field induced from the disks, between the disks.
Now the questions:
1. The view to the problem is from above, so in the geometry you'll see not the disks, but two rectangulars. So, from the geomtry it is a 2D Problem, but wich physical model should I use? Magnetic transient, right?

2. When I draw the rectangulars, which representing the disks, how can I assign the magnetic properties to this rectangulars?

3. How can I assign the speed and direction?

Thanks for viewing, and greetings from Germany.

2. Jan 25, 2013

### pumila

Are you working on the Faraday Paradox? Not to clear what you are up to.

3. Jan 25, 2013

### shuhart

No, I am not working on Faraday Paradox.
In the end I want to simulate the magnetic effects on a steel band, that lies in between two moving magnetic fields.

Just today I managed to simulate the static magnetic field, from one permanent magnet.

Better explanation of the problem:

1. I have two permanent magnets. Lets say Magn1 and Magn2.
2. These magnets are positioned on the Y-Axis, the coordinates are: Magn1 (0mm, 6mm)
and Magn2 (0mm, 0mm).
3. The direction of the field is: Magn1 plus Y-Axis, Magn2 minus Y-axis.
(I know now how to simulate the steps 1-3)
4. (Now it is going to be complicated). Both Magnets 1 and 2 are moving in X direction, with same speed.
5. (these step is the end step). Between two magnets lies the steel band, and I want to know how the moving field interacts with the steel band.

Thank you for the reply.

4. Jan 25, 2013

### pumila

It would seem possible to analyse the magnetic field (as if it were stationary) and the motion-induced electric field separately.

You mention the disks rotate, but in the second note you say they are moving. The results are different for linear motion and rotating motion.

Assuming rotating disks....

I do not know the orientation of the steel band, presumably it is a flat leaf bent round into a hoop. However, my first take on this is that the electric flux paths indicate no eddy currents (refer to Faraday Paradox) partly because the induced electric field (not that there is much, if any, given the geometry) is purely radial and constant in strength and direction. If so, only the magnetic field is involved, so the rotation of the magnets and associated induced electric field should not be significant.

Then the magnetic field would have little effect either, because the magnetic fields oppose each other so in the middle there is a balance point where the band sits.

As mentioned, linear moving magnets have a different solution because there will be eddy currents which create their own forces.

Is this where your own analysis leads?

5. Jan 25, 2013

### shuhart

Good idea. In the real experiment there are two (non magnetic) disks, with many magnets assigned on the boarders of the disks.
In the model, you are looking on the top of the disks, so you can see the line of magnets and the space between the disks. Here is the picture how I mean it: