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Lookup NU author(s): Dr Vladimir Zivkovic
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
We used speckle visibility spectroscopy (SVS) to measure the time-resolved dynamcis of avalanching down the inclined free surface of a granular material in a half-full rotating drum operating in the slumping regime. The distribution of the avalanche period, td, rest time between them, tr, and peak particle velocity fluctuation, \delta \nu 2p are all Normally distributed. Whilst the distributions of the two times at the top and bottom of the free surface are very similar, the particle velocity fluctuation is greater at the bottom of the free surface than at the top. The rest time is observed to be inversely related to the drum speed. Combining this with the relation of tr and the difference of the upper and lower angle of repose for the granular material, \Delta \Theta, we find that the latter decreases linearly with increasing rotational speed. We also observe that td increases in a linear fashion with the drum speed. Using the relation of tr and the distance that particles have to move during an avalanche, we further find that a new scaling relation of the mean number of avalanches required to traverse the free surface with drum speed. We find that the slumping frequency increases with the rotating speed before becoming constant in the slumping-to-rolling transition region. Finally, we find that the average peak of the fluctuation speed of the avalanche, \delta \nu p2, increases linearly with the drum speed.
Author(s): Yang H, Li R, Kong P, Sun QC, Biggs MJ, Zivkovic V
Publication type: Article
Publication status: Published
Journal: Physical Review E
Year: 2015
Volume: 91
Issue: 4
Online publication date: 30/04/2015
Acceptance date: 16/04/2015
Date deposited: 01/05/2015
ISSN (print): 1539-3755
ISSN (electronic): 1550-2376
Publisher: American Physical Society
URL: http://dx.doi.org/10.1103/PhysRevE.91.042206
DOI: 10.1103/PhysRevE.91.042206
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