Researchers explain emergence of bacterial vortex
The chaotic motion of all those individual swimmers spontaneously organizes into a swirling vortex, with bacteria on the outer edge of the droplet moving in one direction while those on the inside move the opposite direction. Researchers from Brown University and the University of Cambridge have explained for the first time how that dual-motion vortex is generated. Using computer modeling and a clever experiment, the researchers show that the fluid flow generated by all those tiny swimmers explains that strange two-way motion. But individuals swimming along the outside of the circle created a flow in the fluid in the opposite direction from the direction they’re swimming. The experiment showed that all the bacteria were indeed attempting to swim in the same direction.