Microspheres in a fluid, spinning in opposite directions, create flow patterns that affect other particles. Computer simulations show the particles self-assembling into different structures at different concentrations: bands, small swirls, a single large vortex.
From flocks of starlings to schools of fish, nature is full of intricate dynamics that emerge from the collective behavior of individuals. In recent years, interest has grown in trying to capture similar dynamics to make self-assembling materials from so-called "active matter."
(Distributed June 5, 2015)