Question about force calculation

["Rob " <rtickle@xxxxxxxx>]

Hi David,

First of all, many thanks for an impressive piece of freeware - this 
program is very nice! I've been searching for a public domain piece 
of FEM software for magnetics, and my search ended when I found yours.

I am currently modelling a simple C-core type electromagnet with 
circular pole faces. I am trying to get a calculation of the pull 
force on the pole pieces, but not sure how to approach this. I've 
tried drawing a closed contour which encloses a pole face around one 
of the pole pieces, with 3 sides in air and the 4th intersecting one 
of the core arms, but the force value I got seemed very high. I read 
in the manual about the problems related to crossing boundaries of 
materials with varying permeability and problems with mesh size. I'm 
wondering if the large value I got is due to these issues and if 
there is a better way to do this calculation. 

All the examples I've seen of force calculations are of parts which 
are isolated from the rest of the geometry, allowing closed curves in 
air to be used. Any suggestions on how to approach this? 

Thanks very much, Rob