So now look at the leftmost powder in a line of DUST. Powders can move into three places without external air interference. Down, Down-left, Down-right. Only Down-right is open. So it moves there. Now look at the next DUST, it again only has Down-right! Every particle in the line will only have one possible movement location, the bottom right corner from it. So they all move there. That is all, it's not a bug, it's just weird to look at.
This happens for two perfectly explainable reasons. First, the default order of particles when loading a save is top to bottom, right to left. Particles get updated / moved in that order.
This isn't really a bug, it's just how gravity acts upon particles when there's no air friction to make it spread out. I wonder if it would work the same way in a real-life vacuum chamber?
it might be that with air sim off, gravity has a canstant effect on the particles...
LOL LOL LOL 1912127 a "practical" application!