Surface level migration in vibrating beds of cohesionless granular materials

Abstract

Surface level migration in vibrating beds of cohesionless granular materials is investigated experimentally, numerically, and theoretically. The difference in surface levels of narrow and wide regions is measured for various values of the vessel size, particle size, and frequency and power of vibration. The effects of these parameters on surface level migration are clarified. A molecular dynamics technique is used to calculate various physical quantities, especially, wall shear stresses. It becomes evident that side walls exert downward forces on particles and the friction between particles and walls play an essential role in surface level migration. A vertical force balance on a layer of the material is analyzed and a formula for the difference of surface levels is derived. The theoretical results are compared with numerical ones. The theory and the simulation agree qualitatively.