Disentangling the Free-Fall Arch Paradox in Silo Discharge.

摘要: Several theoretical predictions of the mass flow rate granular media discharged from a silo are based on spontaneous development free-fall arch region, existence which is still controversial. In this Letter, we study experimentally and numerically particle through an orifice placed at bottom 2D 3D silos. The implementation coarse-grained technique allows thorough description all kinetic micromechanical properties in outlet proximities. Though does not exist as traditionally understood--a region above particles have negligible velocity below fall solely under gravity action--we discover that pressure displays well-defined transition position scales with size. This universal scaling explains why picture has served approximation to describe discharge