1. Introduction
Dating back to Smith's work on density segregation in a jarred
vessel
[1]
, researchers have been fascinated by the tendency of shaken
granular mixtures to seemingly defy physics
—
larger particles rising to
the surface despite the bottom of the vessel being the more
energetically favorable position. Examples of similar phenomena
abound in everyday life, such as larger grains rising to the top of a
muesli mixture, in geophysical occurrences, like the rise of a large
stone in a
fi
eld after a freeze
–
thaw cycle and in catastrophic events,
akin to
fi
nding the larger boulders at the bottom of the mountain and
the smaller ones near the top after a landslide or avalanche. In
addition to its abundance in nature, size segregation plagues
industrial processes, contributing greatly to the meager 60% operating
ef
fi
ciency of most solids processes
[2]
. More recently, endeavors to
understand size segregation in rotating drums
[3]
, shear cells
[4]
and
industrially relevant blenders
[5]
have exposed remarkable segrega-
tion patterns and have even offered some adjustments to boundaries
and operation parameters to minimize this segregation. However, still
lacking are speci
fi
c recommendations to alter the components of the
granular mixture to minimize the tendency of a system to segregate.