http://weelookang.blogspot.sg/2015/08/ejss-brownian-motion-model.html

Brownian motion

This is a simulation of brownian motion of a particle that collides with a large set of smaller particles which move with uniform motion in different random directions.

For more info:

http://weelookang.blogspot.sg/2010/06/ejs-open-source-brownian-motion-gas.html