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.
(June 2, 2015) 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.”
Brown University researchers Kyongmin Yeo, Enkeleida Lushi,
and Petia Vlahovska have shed new light on a particular class of active matter
called active colloids — collections of tiny moving particles suspended in
fluid. Using numerical models and computer simulations, the researchers show
how spinning particles, pushed about by the fluid flows created as each
particle spins, can arrange themselves into an array of emergent macro-scale
patterns.