[Click for the bga-12.fe datafile in a second window.]
This model replaces the pads with equivalent line integrals around
the pad rim. The behavior is exactly the same as bga-11.fe.
Notable features:
The top and bottom pad facets are not onerous in this series of models,
especially with "no_refine" to keep their numbers down and no freedom
for the contact lines on the pads to move off the pad rims. But this
model
illustrates how one could remove the pad facets, if one should want.
The lower pad facets make no contribution to either energy (having
tension 0) or to volume (since z = 0). Recall that the default volume
calculation is done by integrating z dx dy over the surface. Hence
the lower pad facets can simply be deleted from the datafile.
The upper pad makes a contribution to the volume, which can be
replaced by integrating z x dy around the top pad rim edges. This
is implemented by a "content" integrand for boundary 1. (I use "content"
as the general-dimensional word for volume.) Note the integrand has
a minus sign, which is necessary because of the Evolver's convention
for the sign of content integrands: edges oriented as positive boundary
of facets that are postive boundary of a body contribute positive content.
Here the top edges have negative orientation in the definition of the
body faces, so the negative sign is necessary. You should always check
to make sure your volumes come out to what you expect on the initial
datafile.
The upper pad makes no contribution to surface tension energy, but
it does make a contribution to gravitational energy. On facets, the
gravitational energy is calculated as the integral of G*density*z2/2 dx dy,
so an equivalent edge integral is G*density*z2/2*x dy. Note that I am
using the fact that dy slices are horizontal.
