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and the boundary, if any.
In its pre-"jammed" mode when the particle density is
low and they are mobile, the compression and expansion
simulating
dynamic [[granular flow]].
External forces, such as gravitation, can be easily
introduced, as long as the intercollision motion
of each particle can be represented
by a simple one-step calculation.
A substantial limitation of the original LS protocol
is that it was designed to practically work only
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the processed event time stamp,
the particle state (including
position and velocity), and, perhaps, the "partner"
which could be
another particle or boundary identification,
the one with which the particle collided in the past,
and a new event proposed for a future processing
with a similar set of parameters.
At processing the scheduled event for a particle,
what was previously the new event, is declared
to be the old one,
whereas the next new event is being scheduled,
with its new time-stamp, state, and new partner.
The LSA successfully achieves the jamming state
when collision rates of different particles
remain comparable (and those rates may and usually do
increase in simulated time without an upper bound).
However, a possibility exists
that a small fraction of the particle ensemble,
in the limit even a single particle,
would exhibit an ever increasing collision rate
not only in the absolute term, but also
as compared with the rates of collisions
in the rest of the ensemble.
Then the simulation might not be able
to advance beyond a point in simulated time
and at that point the jamming would not be
close
to its completeness.
The same failure of being "stuck in time"
can occur when using LSA
just for simulating a granular flow,
without the particle compression
or expansion. The failure mode
has been recognized by the practitioners
of the LSA and
techniques to avoid the failure have
been proposed.
== Examples of use ==
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