Abstract
Both heavier- and lighter-than-liquid particles will
float on liquid-air surfaces. Capillary forces cause the particles to cluster
in typical situations identified here. This kind of clustering causes particles
to segregate into islands and bands of high concentrations in thin liquid films
rimming the inside of a slowly rotating cylinder partially filled with liquid.
A second regime of particle segregation, driven by secondary motions induced by
off-center gas bubbles in a more rapidly rotating cylinder at higher filling
levels, is identified. A third regime of segregation of bi-disperse suspensions
is found in which two layers of heavier-than-liquid particles that stratify
when there is no rotation, segregate into alternate bands of particles when
there is rotation*.