Simulation of small particle penetration in a random medium

Random packings of identical spheres of unit diameter were built according to a procedure in which spheres are released one after another along randomly positionned vertical trajectories and then follow the path of steepest descent on the others until they reach a stable position under gravity. Once a packing has been built, smaller spheres, of diameter d does not diverge but saturates to c 11 and the histogram N reaches an exponential shape whose large ΔZ tail is well fitted by N α exp(−0.103 ΔZ). It is shown that such behavior is due to a non zero proportion of equilateral triangles of tangent spheres in the random packing