Re: Magnetic Field Source

["David Meeker" <dmeeker@xxxxxxxx>]

--- In femm@xxxxxxxxxxxxxxx, "tano1938" <rgarritano@xxxx> wrote:
> I'm a first time user of femm. I've been working through the 
> tutorial and am confused by the units and significance of 
> the "Magnetic Field Source", i.e. Weber/meter. How does it relate to 
> Magetic Intensity (H) or Flux Density (B). Since it is a user input, 
> I'd like to know how to apply it to a practical situation. I've 
> never had to use it before, but I've never used an FEA program before 
> also.
> 
> Thanks for your help.

In this example, the idea was to model a block sitting in a magnetic
field that would be constant in the absence of the block. In this
case, you can set the magnitude of the field, over a square domain, by
setting the potential at one edge of the domain to be zero, and the
potential at the other edge of the domain to be (flux
density)*(length) where (length) is the length of one of the sides of
the square.

This is perhaps not the most typical sort of problem. In most cases,
the field is driven by coils or permanent magnets that are explicitly
modeled as part of the solution domain--most of the included example
problems are like that. In those cases, you can define potential to
be zero at some suitably far distance from the objects of interest (or
you can use one of the more subtle "open boundary" techniques
discussed in the manual).

Dave.