Magnetically Sprung Electromagnetic Generator

Hi guys,

I have built a magnetically sprung electromagnetic generator for harvesting energy from machine vibration. Its basically three magnets in a tube, one fixed at either end and one floating in the middle (as all the like poles face each other). There is a copper coil around the middle of the tube. When the tube oscillates up and down the center magnet passes through the coil generating a voltage.

I'm trying to use comsol to model the movement of the floating magnet as the tube oscillates in the z direction (vertically).

I created a 2D axisymmetric model with magnetic fields and moving mesh. I used predescribed mesh displacement with a sine function to oscillate the fixed end magnets in the z direction. I used Amperes law to define the remnant flux density of the magnets. So far I've only been able to plot the change in electromagnetic force exerted on the floating magnet over time if I fix it in one place.

Is there a way to allow the floating magnet to move freely based on the force exerted on it by the other magnets, its mass and gravity? and then plot its displacement?

Any help would be greatly appreciated.

Cheers