Sand has light part and heavy part,for the heavy part,its gravity is far more than the windforce,moving like rigidbody .For rendering , the best way is using volume ,but Pyro can't simulate rigidbody.

I figure out some way using pyro to simulate sand,but it's not perfect and hard to control.

Really hope sidefx can make a sand solver.

no need.. you have vellum grains, or you have pop advected by Pyro... many ways to do this.