Falling process of a rectangular granular step

Hsien Ter Chou, Ching Fang Lee

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4 Scopus citations


This study experimentally investigates the falling process of a dry granular step in a transparent plexiglass chute by particle image analysis. Three types of uniform spherical beads and one type of quartz sand were piled up with various bed slopes and widths to elucidate their flow characteristics. The surface angles during the early slipping phase are close to the failure angles that are associated with the active earth pressure, based on the Mohr-Coulomb friction law. For a given size of particles (d) and slope (θ), the retreating upper granular surface follows a theoretical curve, and dimensionless mobile length decreases as the dimensionless time parameter t*increases. Velocity profiles measured at the side wall exhibit an exponential-like tail close to the static region at the bottom of the chute. As determined by the conservation of mass and momentum, the relationship between the characteristic velocity and the characteristic depth is linear in the transient flow.

Original languageEnglish
Pages (from-to)39-51
Number of pages13
JournalGranular Matter
Issue number1
StatePublished - Feb 2011


  • Avalanches
  • Falling process
  • Granular flows
  • Granular step
  • Side wall effect


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