Sshape of a granular pile in a rotating drum

Abstract

The shape of a granular pile in a rotating drum is investigated. Using Discrete Elements Method (DEM) simulations we show that the "S shape" obtained for high rotation speed can be accounted for by the friction on the end plates. A theoretical model which accounts for the effect of the end plates is presented and the equation of the shape of the free surface is derived. The model reveals a dimensionless number which quantifies the influence of the end plates on the shape of the pile. Finally, the scaling laws of the system are discussed and numerical results support our conclusions.

Foams in a rotating drum: An analogy with granular materials

“…As observed with foams, the deformations of the granular assembly interface depend on the cell angular velocity ω. The inclination angle as well as the S-shape amplitude increase with ω [7,24,25]. These observations clearly evidence the similarities between foams and granular materials.…”

Erosion and deposition in depth-averaged models of dense, dry, inclined, granular flows

“…One or the other may be constant. For example, in a steady flow down the surface of a heap in a cylindrical drum that rotates with constant angular velocity, the position of the bed is independent of the time, but the particle velocity normal to the bed varies with distance from the center [8,9]. In contrast, we focus here on situations in which the particle velocity at the bed is negligible, but the position of the bed is a function of time alone.…”

“…The simplest case is when the motion of the interface between the bed and flow is known, as in experiments in a rotating drum [6,7]. In this case, the rate at which material enters or leaves the flow is known and the stress ratio at the surface of the bed has its yield value [8,9]. The more complicated situation is when the motion of the interface must be determined.…”

Granular Free Surfaces

“…In that case, the axis of rotation is horizontal. Beautiful calculations of the resulting mixing can be found in [26], while the nature of the free surface is discussed in [48].…”