Study of an "automated" rolling droplets system, using Particle Flow. Nothing physically correct at this stage.(far from it), but works in many situations and it´s fun to see. :)
There´s a lot of room for improvement as you can see. Some water droplets rolls against gravity and wind forces... So need to adjust and balance those parameters better.
Test Rendered with : Corona-renderer.com
Heres the project file (3dsmax 2013) -> dl.dropboxusercontent.com/u/12986234/Simple_rain_System_clean.zip