Saw a great Houdini Fluid Sand test here: vimeo.com/14207113 and gave it a shot without fluids.
Particle Flow Toolbox#3.
Sand flings off based on speed, an animated grayscale map and erodes from the outside to the inside like real sand.
The mesh has some issues, hence the peaking sand at the knee.
Rendered with Krakatoa, 1.5Mio particles.
To do: "Island detection" When a chunk of sand is not connected to the big bulk anymore it has to go naturally...