Getting my self familiar with grain solver doing some stress and stability tests, I thought it might be helpful to share. As you can see I added some straws but they don't rotate as what you would expect following the stream, instead you'll need to use RBD Grains.
I tried creating the same effect with vellum but failed, the isolated grains keep jumping here and there, and also it doesn't clump beautifully as with grain, once the constraint are broken in vellum they wont comeback again unless you manually added them through a sop solver inside the dop network, but never tried that.