  A fluidized bed is basically a suspension of granular material by an
ascending fluid in a tube, and it has a rich dynamics that includes clustering
and pattern formation. When the ratio between the tube and grain diameters is
small, different behaviors can be induced by high confinement effects. Some
unexpected and curious behaviors, that we investigate in this paper, are the
crystallization and jamming of grains in liquids with velocities higher than
that for incipient fluidization, supposed to maintain the grains fluidized. In
our experiments, performed in a vertical tube of transparent material,
different grains, water velocities, resting times, and velocity decelerations
were used. An analysis of the bed evolution based on image processing shows
that, after a decreasing flow that reaches a velocity still higher than that
for incipient fluidization, grains become organized in lattice structures of
high compactness, where they are trapped though with small fluctuations. These
structures are initially localized and grow along time, in a similar manner as
happens in phase transitions and glass formation. After a certain time, if the
liquid velocity is slightly increased, jamming occurs, with grains being
completely blocked and their fluctuation disappearing. We show that different
lattice structures appear depending on the grain type. Our results provide new
insights into fluidization conditions, glass-like formation and jamming.
