All--
I've put up a new beta version of femm 3.0 in the "files" section of the
mailing list website at:
http://groups.yahoo.com/group/femm/files/
I'd be interested in feedback/bug reports, especially with respect to the new
functionality that has been implemented.
The most significant change to this version is the addition of periodic and
antiperiodic boundary conditions. This was sort of the last "big" feature
that I wanted to put into the 3.0 version before making it a "release" rather
than a "beta." One uses this sort of boundary condition by choosing
"Periodic" or "Antiperiodic" in the "BC Types" drop list in the boundary
property dialog. Each defined periodic boundary condition should be applied
to two and only two segments or arc segments that are meant to be connected
periodically. If there are multiple pairs of segments or arcs, you have to
define multiple boundary conditions.
Anyhow, I have also posted a zip file containing two examples that employ
periodic and antiperiodic boundary conditions. One sample is the switched
reluctance motor pictured at:
http://www.elec.gla.ac.uk/groups/speed/software/feashot.html
Just as on this web page, periodic boundary conditions have been applied so
that only part of the motor need be modeled.
The second example I have taken from the paper,
Lowther, D.A., Freeman, E.M., and Forghani, B., "A sparse matrix open
boundary method for finite element analysis," IEEE Transactions on Magnetics
, 25(4):2810-2812, July 1989.
This is an example of a pretty slick way that one can go about modeling open
boundary problems through the use of periodic boundary conditions. There are
also a couple of other interesting papers in Trans. Mag. by the Infolytica
guys that explore other aspects of this open boundary approach.
Anyhow, I the implementation of the periodic and antiperiodic boundary
conditions seems to run ok, but there could be bugs that pop up due to other
people testing it in ways that I might not have considered. It turned out
that there were a lot more subtleties in implementing these boundary
conditions than one might think, so there is certainly the possibility of
bugs. One thing that is different about these bcs (but not a bug) is that
triangle gets called twice during the meshing of problems with pbcs and apbcs.
I also modified the program so that it looks at a file called "colors.dat"
that lives in the femm30\bin directory for definitions of the colors used in
the various modules of femm. A femm user who is colorblind turned me on to
the necessity of being able to modify the color scheme that femm uses. And
it seems like nobody but me likes the mesh rendered in yellow.... Anyhow,
this is a text file, and you change around the colors by editing it with
notepad or whatever.
This version also has a manual that has been partially updated to 3.0 from
2.1a, but there's still quite a bit of work left on the documentation.
Dave Meeker
--
http://members.aol.com/dcm3c
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