I've been working on a setup to release sand from a rest position similar as seen in the first 13 seconds of this movie:


Made sure clumping is properly distributed by setting the attractionweight attribute.
Using POP awaken to get the simulation started. So far I get a very even drop of all the grains.
I am looking to get a more gradual release, with some stragglers causing fine streams after the bulk of the grains dropped as seen in the video above.

All suggestions welcome.