Surface band segregation and internal convection in rotating sphere densely filled with granular material: Experiments

  title={Surface band segregation and internal convection in rotating sphere densely filled with granular material: Experiments},
  author={Weitao Sun},
  journal={Physics of Fluids},
  • Weitao Sun
  • Published 24 August 2021
  • Physics
  • Physics of Fluids
While granular segregation in partially filled containers has been studied extensively, granular dynamics in densely filled spheres is not fully understood. Here, surface band segregation and granular convection are reported in a rotating sphere of highly compacted glass beads. Distinct from Rayleigh–Bénard convection, granular convection has a butterfly-shaped structure with vortexes of alternating layers of small/large beads, which is stable and independent of the sphere size. Two concentric… 

Figures from this paper


Oscillations, cessations, and circulation reversals of granular convection in a densely filled rotating container.
Oscillatory modulations of the convection velocity, cessations and spontaneous reversals of the circulation are described, which are absent in multiroll granular convection.
Size segregation and convection of granular mixtures almost completely packed in a thin rotating Box
  • Awazu
  • Materials Science, Medicine
    Physical review letters
  • 2000
A global convection appears after a radial segregation pattern is formed, and this convection induces an axially segregated pattern which is qualitatively reproduced with this simulation.
On the brink of jamming: granular convection in densely filled containers.
It is demonstrated in an almost compactly filled flat (Hele-Shaw) cell, where slow horizontal rotation simulates a variable gravitational force, that unexpected dynamic structures may arise under geometrical restrictions.
Particle Segregation in Dense Granular Flows
Granular materials composed of particles with differing grain sizes, densities, shapes, or surface properties may experience unexpected segregation during flow. This review focuses on kinetic sieving
Segregation of granular mixtures in a spherical tumbler.
This study describes axial segregation of bidisperse granular mixtures of glass beads in a spherical container, rotating about its horizontal axis, which evidences a collective pattern forming mechanism.
Density waves and coherent structures in granular Couette flows
Density inhomogeneities in granular flows can dramatically influence microscopic and macroscopic properties. Here, we numerically examine dilute rapid granular flows in the Couette geometry via
Thermal Convection in Granular Gases with Dissipative Lateral Walls.
It is shown that a horizontal temperature gradient leads always to a granular thermal convection that is essentially different from ordinary bulk-buoyancy-driven convection (BBD TC), and molecular dynamics simulations indicate that at large gravity or number of grains the DLW TC is barely detectable.
DEM study of the size-induced segregation dynamics of a ternary-size granular mixture in the rolling-regime rotating drum
Segregation induced by size, shape, or density difference of the granular material is inevitable in both natural and industrial processes; unfortunately, the underlying mechanism is still not fully
Simulating granular media on the computer
Granular materials, like sand or powder, can present very intriguing effects. When shaken, sheared or poured they show segregation, convection and spontaneous fluctuations in densities and stresses.
Mixing and segregation of granular matter: multi-lobe formation in time-periodic flows
We study size segregation in two classes of granular systems in time-periodically forced quasi-two-dimensional tumblers. In dry granular systems (DGS), particles are immersed in air, whereas in