Surface velocity in three-dimensional granular tumblers

Nicholas A. Pohlman*, Steven W. Meier, Richard M. Lueptow, Julio M. Ottino

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


A fundamental characteristic of granular flows is that they are typically restricted to thin layers of rapid surface flow. Thus, a complete understanding of surface flows is key for an accurate representation of the dynamics of the entire flow. Experiments were conducted in three-dimensional tumblers: cylindrical tumblers of various diameters, a double-cone tumbler, and a spherical tumbler, the Froude number for the last two being a function of the local geometry and ranging from 2.6 × 10-5 to 7.5 × 10-4. Surface velocity measurements for 1 mm and 2 mm glass particles were obtained using particle tracking velocimetry. Results indicate that the streamwise surface velocity at the midpoint of the flowing layer is a linear function of local flowing layer length, regardless of tumbler shape, particle size, rotation rate, and fill fraction. In addition, the axial velocity of particles at the free surface is negligible. These results are key for the development of three-dimensional models of granular flows.

Original languageEnglish (US)
Pages (from-to)355-368
Number of pages14
JournalJournal of fluid Mechanics
StatePublished - 2006

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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