Fill a jar with little spheres

[HHbomb]

Thank you very much, I know now for time step    but I wasn't aware gravity matter so much... (sorry for my poor english)

Gravity doesn't matter technically be the amount the particles move each frame matters. So lets say your gravity is -0,1 you need 1/2 Substep for example, then with -0,2 gravity you need 1/4 Substep to get the same calculations. So the more the particles move each frame the more substeps you need.

Thanks, that is clear for me now. But as objects accelerate with gravity, more they travel more they go fast (if they don't collide) and not linearly. So more they travel more I need to decrease substeps... That need some practice !