The following videos demonstrate using the grain solver nodes in SideFX Houdini 15.5 with dynamic interaction.
The final result.
In this video we’re seeing that the particles are in a sleeping state (shown by their red color). They are then woken up by a dynamic object (hidden) to activate them.
In this video we’re seeing further into the process of how the activated particles are activating their neighboring particles by seeking within a given area for their presence. This is shown as a volume area (that smokey stuff you’re seeing) around each particle.
This scene was setup for rendering using the Houdini to Arnold Basic Studio setup that is freely available HERE.