Ping-Pong Ball Avalanche Experiments

  1. William McCaffrey,
  2. Ben Kneller and
  3. Jeff Peakall
  1. J. McElwaine and
  2. K. Nishimura

Published Online: 17 MAR 2009

DOI: 10.1002/9781444304275.ch10

Particulate Gravity Currents

Particulate Gravity Currents

How to Cite

McElwaine, J. and Nishimura, K. (2001) Ping-Pong Ball Avalanche Experiments, in Particulate Gravity Currents (eds W. McCaffrey, B. Kneller and J. Peakall), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304275.ch10

Editor Information

  1. School of Earth Sciences, University of Leeds, Leeds, LS2 9JT, West Yorkshire, UK

Author Information

  1. Institute of Low Temperature Science, University of Hokkaido, North 19 West 8, Kita-Ku, Sapporo 0060-0819, Japan

Publication History

  1. Published Online: 17 MAR 2009
  2. Published Print: 24 APR 2001

ISBN Information

Print ISBN: 9780632059218

Online ISBN: 9781444304275

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Keywords:

  • ping-pong ball avalanche experiments;
  • snow avalanches measured and observed in Shiai valley, Kurobe;
  • ball measurements;
  • measuring air velocity in particulate flows being difficult;
  • granular flow experiments with styrene particles and front velocity found to increase with number of balls;
  • flow structure and ball velocities;
  • lower boundary effects and a mixing region behind head

Summary

Ping-pong ball avalanche experiments have been carried out for the last three years at the Miyanomori ski jump in Sapporo, Japan, to study three-dimensional granular flows. Up to 550 000 balls were released near the top of the landing slope. The balls then flowed past video cameras positioned close to the flow, which measured individual ball velocities in three dimensions and air pressure tubes at different heights. The flows developed a complicated three-dimensional structure with a distinct head and tail, lobes and ‘eyes’. ‘Eyes’ have been observed in laboratory granular flow experiments and the other features are similar not only to snow avalanches, but also to other large-scale geophysical flows. The velocities attained showed a remarkable increase with the number of released balls. A power law for this relation is derived by similarity arguments. The air pressure data is used to deduce the structure of the air flow around the avalanche and, in conjunction with the kinetic theory of granular matter, to estimate the balance of forces in the avalanche head.