I was making another ident thing in collaboration with Man vs Machine recently and it called for a big egg made out of coloured layers of sand to fall/collapse to the ground.
Sand is always tricky - perhaps more so than water and fluid simulations - as it moves and flows like fluid but has friction and rigid body bahavior per-particle. This means when you are dealing with MILLIONS of particles - things can get pretty difficult to control and simulate.
I decided to pursue a solution with Naiad - utilising alot of custom channel controls to try and get the volume of sand to collapse in chunks and settle quickly.
Heres some R&D I was playing with early on as a proof of concept. I was combining massive viscosity values and creating multiple particle tags via lots of small fractured bits of geometry.
I plan to put together a more indepth look at this stuff soon
NAIAD sand RD from Matt Chandler on Vimeo.