2009

For example, if a particle travels along a parabolic path, its motion has
both linear and circular components. The circular component is greatest
at the top of the parabola. If a particle travels in a full circle in one second,
the rate is 360; if it travels in a half circle, the rate is 180.
Potential usage: When a particle is forced to turn too sharply, it might
explode or change its type of movement. For example, missiles chase a jet
fighter, which maneuvers to elude the missiles. The missiles are forced to
change their course rapidly, but the missile construction cannot stand the
fast change in steering, so the missiles blow up or disintegrate.
TIP You can test steering rate by setting the particle speed with Speed By Icon
on page 2876, and linking the Speed By Icon operator icon to a circular path.
■ True When Accelerates Returns a True value when the particle velocity
is increasing in value.
■ True When Decelerates Returns a True value when the particle velocity
is decreasing in value.
Test True if Particle Value Lets you specify whether the test passes particles
on to the next event if the speed test succeeds or fails. Available for all tests
except True When Accelerates/Decelerates. Default=Is Greater Than Test Value.
By default, Speed Test returns True if the value tested for exceeds the Test
Value quantity, but you can choose Is Less Than Test Value as well. For
example, if you use the Velocity Magnitude test type and set Test Value=200
and Variation=0, and choose Is Less Than Test Value, then particles will move
to the next event only when they travel faster than 200 units per second. Any
particles traveling 200 units per second or slower stay in the current event
unless they later exceed that speed or another test returns True.
Test Value The specific speed or acceleration to test for. The unit of
measurement depends on the type of test; see above. Default=300.0.
Variation The amount by which value tested for can vary randomly.
Default=0.0.
To obtain the actual test value for each particle, the system multiplies the
Variation value by a random number between -1.0 and 1.0, and then adds the
result to the Test Value setting. For example, if Test Value=300 and
Variation=10, then tested value for each particle would be between 290 and
310.
Particle Flow | 2997