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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@12028 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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sjplimp 2014-05-27 14:02:43 +00:00
parent e5e877dd3f
commit e09f40c9d0
2 changed files with 22 additions and 2 deletions
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12
doc/fix_wall_region.html
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@ -76,11 +76,21 @@ points suffer from inaccuracies. The basic problem is that the
outward normal of the surface is not continuous at these points. This
can cause particles to feel no force (they don't "see" the wall) when
in one location, then move a distance epsilon, and suddenly feel a
large force because they now "see" the wall. In the worst-case
large force because they now "see" the wall. In a worst-case
scenario, this can blow particles out of the simulation box. Thus, as
a general rule you should not use the fix wall/region command with
<I>union</I> or <I>interesect</I> regions that have convex points or edges.
</P>
<P>IMPORTANT NOTE: Similarly, you should not define <I>union</I> or
<I>intersert</I> regions for use with this command that share a common
face, even if the face is smooth. E.g. two regions of style block in
a <I>union</I> region, where the two blocks have the same face. This is
because LAMMPS discards points that are part of multiple sub-regions
when calculating wall/particle interactions, to avoid double-counting
the interaction. Having two coincident faces could cause the face to
become invisible to the particles. The solution is to make the two
faces differ by epsilon in their position.
</P>
<P>The energy of wall-particle interactions depends on the specified
style.
</P>

12
doc/fix_wall_region.txt
View File

@ -73,11 +73,21 @@ points suffer from inaccuracies. The basic problem is that the
outward normal of the surface is not continuous at these points. This
can cause particles to feel no force (they don't "see" the wall) when
in one location, then move a distance epsilon, and suddenly feel a
large force because they now "see" the wall. In the worst-case
large force because they now "see" the wall. In a worst-case
scenario, this can blow particles out of the simulation box. Thus, as
a general rule you should not use the fix wall/region command with
{union} or {interesect} regions that have convex points or edges.
IMPORTANT NOTE: Similarly, you should not define {union} or
{intersert} regions for use with this command that share a common
face, even if the face is smooth. E.g. two regions of style block in
a {union} region, where the two blocks have the same face. This is
because LAMMPS discards points that are part of multiple sub-regions
when calculating wall/particle interactions, to avoid double-counting
the interaction. Having two coincident faces could cause the face to
become invisible to the particles. The solution is to make the two
faces differ by epsilon in their position.
The energy of wall-particle interactions depends on the specified
style.