Flow visualization is one of most imporpant techniques of the numerical
fluid dynamics. Basic algorithms are almost common in various software
for it. In this lesson, floating particle without weight nor dimension
are applied to trace the flow field and streak line. As you know,
the streak line is different from the stream line. While both are coincided
in steady state flow, the streak line is more applicable in Laglangian
treatment. The particles are input from in-flow boundary, and disappear
from out-flow boundary. Then they have their life-timeand the programmer
has to control them, because the simulator will stop by memory restriction,
if the particle can not die. In this chapter, "Particle" class is introduced,
which have, of course, life and its history in floating. The programmer
usually needs a lot of particles for visualization, for a few particle
can not cover the shape of flow. The number of particles is to be decided
by programmers' dicision which are related to the capability of CPU and
memory.
In the "Particle" class, Vector and tensor treatment is dominant, and
then it is easier to apply this class to 3D animation.
The particle motion is a kind of heuristic calculation like the
nature. It is worth the name of simulation.