Smoothly animating hourglass.
This uses bolian operations for the bulk of the sand rendered as volumteric textures, plus a particle system for the falling sand. It renders very fast. Texture from cgtextures.com
Good job, yogyog
This seems like a great achievement. The granules are realistic.
The thing I notice is that in real life the level of the granules in the upper chamber is not completely flat: the granules fall from the centre of the mass in the upper chamber, leaving a pit or dip and that the pit grows as more sand vacates, so the level of granules against the glass is higher than in the middle.
Watch http://www.youtube.com/watch?v=GQ3GbndcMCQ near the end to see what I mean about the dip.