Figure 1
D. C. Rapaport, Phys. Rev. E 73, 025301(R) (2006)

Steady as she goes. As shown in this computer simulation, classic convection “rolls” form a stable hexagonal pattern on the surface of a fluid being heated from below, as material rises and falls in closed loops within separate regions. When specialized nanoparticles are added to water and uniformly distributed, the convection pattern never stabilizes. And the convection flow can be turned on or off based on the initial arrangement of the particles. (See animation below.)