Velocities of irregular particles in a continuously avalanching surface flow within a rotating drum

Velocities of irregular particles are difficult to measure and analyse owing to their irregular shapes. In this study, the method of spatial filtering velocimetry is used to measure the velocities at which the particles flow on a surface in the roll mode. The images of the particle flow show that the surface is not a straight line but mound exists due to the accumulation of particles at the middle of the drum which influence the velocity profile. The variation of the velocity distribution of irregular particles with drum speeds, particle sizes, and drum diameters is presented and discussed in the paper. The results indicate that there were two velocity peaks in the velocity profile of irregular glass sand at a relatively lower rotating speed. Furthermore, with the increase in the drum speed, the middle valley in the profile gradually moves to the upper right and merges with the second velocity peak, and consequently, there is only one peak in the velocity profile along streamwise direction of the bed surface which is consequently similar to spherical particles velocity profile. (C) 2018 Elsevier B.V. All rights reserved.