How can I accurately calculate mutual inductance between a coil and a magnet?

[HiEdgar]

Hi, All:

I am trying to calculate the mutual inductance between the coil (100 turns) and the magnet. Does anybody know any approaches that may lead a satisfactory answer.

So far, I have been using Neumann's formula which is the formula for mutual inductance, M, between two loops. I treated my magnet as another coil and used Neumann's formula to determine M then. The problem with that is that the diameter of the wires of my coil are finite whereas neumann's formula treats them as infinitisemally small. Because of this, my M became a funciton of magnet's wire diameter, which is not right. Any input is appreciated.

Thank you,

Edgar

 

[anorlunda]

That is a notoriously difficult problem. For other than the simplest geomery, you will need a software tool such as COMSOL.