The simulation is running with 20 frames per second.
Initially, those particles are roated with small frequency(large period).
You can adjust frequency(period) with slide bar.
When you increase the frequency, particle move faster.
However, it seems that the direction of rotation is changing? Why?
At some particle frequency(f=10 or period T=0.1), those particle seems to be freeze (not moving at all)?
Do you know why? Enjoy it!

VIEW or DOWNLOAD ejs xml source
then click to translate strings for selected locale.

Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop.