Lubachevsky–Stillinger algorithm: Difference between revisions

Revision as of 01:30, 26 April 2011

Revision as of 02:51, 26 April 2011

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and the boundary, if any.

In itsthe pre-"jammed" mode when the particle density is

when the density of the particles is

low and when they are mobile, the compression and expansion can be stopped, if so desired, and then the LSA, in effect, would be

simulating

dynamic [[granular flow]].

It is also easy and sometimes proves useful to

External forces, such as gravitation, can be

un-"jam" or "fluidize" the configuration,

introduced, as long as the inter-collision motion

by decreasing the sizes of all or some of the particles.

Another possible extension of the LSA is replacing

the

hard collision potential

(zero outside the particle, infinity at or inside) with

a piece wise constant potential. Thus modified LSA

would approximate

a molecular dynamic simulation with continuous

short range particle-particle force interaction.

External forces[[force fields]], such as [[gravitation]], can be

also introduced, as long as the inter-collision motion

of each particle can be represented

by a simple one-step calculation.

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[[discrete event simulation]],

the events being particle-particle or particle-boundary collisions.

Ideally, the computationscalculations should have been

performed

with the infinite precision.

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[[event-driven]] fashion, rather than in a

time-driven fashion. This means that almost

no computationcalculation

is wasted on calculatingcomputing or maintaining the positions and velocities

of the particles between the collisions.

Among the [[event-driven]] algorithms intended for

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Volume 34 Issue 2, 1980

</ref>

, the LSA is distinguished by a simpler
[[data structure]]

and data handling.

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the LSA maintains the record of only two events:

an old, already processed event, which comprises

the processed event [[time stamp]],

the particle state (including

(including position and velocity),
and, perhaps, the "partner"

which could be

another particle or boundary identification,

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to be the old one,

whereas the next new event is being scheduled,

with its new [[time- stamp]], new state, and new partner.

As the calculations of the LSA progress,

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low collision rates).

However, a possibility exists

that onalong the approach to a certain simulated time,

a small fraction of the particle ensemble,

even a single particle,

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Then the simulation might not be able

to advance beyond this simulated time,

eventhougheven though the process of jamming would not be

close

to its completeness on the approach to such a time.

The same "stuck in time" failure

can also occur when using the LSA

just for simulating a granular flow,

without the particle compression