The tests were performed with a dry cohesionless sand with a mean grain diameter of
d50 = 0.8 mm. An initially loose sand was obtained by filling the silo from a pipe located
directly above the upper sand surface which was vertically lifted during filling. An initially
dense sand was obtained by filling the silo using a so-called “rain method” (through a vertically
movable sieve located always 250 mm above the upper sand surface in the symmetry-
axis). The silo was emptied gravitationally.