Narayanan Menon (U Massachusetts, Amherst)

Date: Thu. April 4th, 2024, 4:00 pm-5:00 pm
Location: Rockefeller 301

Thinking about sinking: the settling of shaped solids

The gravitational settling of particles in a viscous fluid is a common process in nature and
in industrial contexts. This familiar process is a confounding problem in many-body
physics due to the long-range, directional interactions between sinking particles. After
discussing some known facts and known puzzles in the field, I will present results that
show qualitatively new behaviour when the particles have non-trivial shape and
orientational degrees of freedom, as do snowflakes, plankton, crystals, and other natural
sediment. As examples of the richness that emerges from shape, I will discuss unusual
phenomena in the sedimentation of individual polar and polygonal objects, of pairs of
apolar and polar objects, and of a one-dimensional lattice of apolar discs. Finally, I will
discuss new results on sedimentation of suspensions of discs and rods at finite density.