Abstract
The clustering is critical to understanding the multiscale behavior of
fluidization. However, its time-resolved evolution on the particle level
is seldom touched. Here, we explore both the time-averaged and
time-resolved dynamics of clusters in a quasi-2D fluidized bed. Particle
tracking velocimetry is adopted and then clusters are identified by
using the Voronoi analysis. The time-averaged results show that the
cluster hydrodynamic parameters depend highly on the cluster size and
the distance from the wall. The number distribution of the cluster size
follows a power law
(~nc-2.2)) of
the percolation theory except for large clusters
(nc>100). The time-resolved analysis
shows that the cluster coalescence can be simplified as a collision
between two inelastic clusters, during which the net external force is
roughly zero, and a snowplow model is proposed to predict its energy
loss, ΔE ~ t3/2. The
cluster rupture is suggested to be caused by increasing torque.