LAUSR

Abstract Considerable amount of experimental work has been performed to elucidate the behavior of granular flow inside a rotating drum but yet it is not completely understood. Furthermore, most of these investigations have involved spherical or nearly spherical particles. The extent of the experiments involving non-spherical particles previously carried out was limited by the experimental techniques available for the studies. In this work, a simple imaging method and a speckle visibility spectroscopy (SVS) technique were used to measure the volume fraction and granular temperature of irregular glass sand particles under the slumping regime within a rotating drum. By comparing the temporal variation of the volume fraction of the granular bed with SVS measurement, we found the compaction and dilatancy of the granular flow during a slumping cycle can be easily characterized by granular temperature temporal curves. At different rotating speeds, we found the lower repose angle increases linearly with the rotational speed and the compaction duration is inversely proportional to the critical angle of compaction. We find, in addition, the compaction induced relative motion of particles decreases with the increase of rotational speed, while the avalanche induced motion of particles is independent of rotational speed. Finally, using the mathematical model of avalanche duration and angle of repose proposed by Mellmann to calculate the particle avalanche duration, we found that the compaction of the particle system shortens the avalanche duration.