Lecturer:Prof. Haim Diamant from Tel Aviv University
Abstract:
An arrangement of particles is said to be "hyperuniform" if its density
fluctuations over large distances are strongly suppressed relative to a
random configuration. Crystals, for example, are hyperuniform. Recently,
several disordered materials have been found to be hyperuniform. Examples
are sheared suspensions and emulsions, and random close packings of hard
spheres. We show that externally driven asymmetric particles in a liquid
suspension (as in sedimentation) self-organize hyperuniformly. This
dynamic phenomenon arises from the long-range coupling, induced by the
force and carried by the host fluid, between the concentration of
particles and their velocity. For certain particle shapes the coupling can
lead to the opposite effect -- enhancement of density fluctuations and
instability. We confirm these analytical results in a simple
two-dimensional simulation.