im having difficulty scattering rigid bodies in my sand sim.

ive got them working without the grains,

and in the grain sim, ive converted them to vdb and used that to select grains and delete them, to create holes in the sand where the stones start.

so far so good, but when i sim they sink immediately to the bottom of the sand.

im not sure what density i should give the stones so they have “neutral buoyancy” in the sand?

hm, actually they now shoot out of the sand vertically at extremely high velocity.

edit- i dont think its related to density/mass. ive tried density levels from 1 up to 500,000 and the stones still shoot up out of the grain sim on the first simmed frame.

ive also increased the outer bandwith of the vdb that removes the particles in the volume of the stones, so there is a larger hole around them, but that doesnt seem to help either.