Self-organization of confined microbial suspensions

Courant Institute, NYU

Suspensions of swimming microbes and other forms of active matter are known to display intricate, self-organized spatiotemporal patterns on scales larger than those of the individual motile units. The collective dynamics of swimming microorganisms exhibits a complex interplay with the surrounding fluid: the motile cells stir the fluid, which in turn can reorient and advect them. I will present a computational model that takes into account these cell-fluid interactions and cell-cell forces and that predicts counterintuitive cellular order. Experiments with Bacillus Subtilis bacteria confirm the predictions of a stable swirling vortex in circular chambers or a persistent unidirectional stream in racetracks. These phenomena emerge as a result of the complex interplay between the swimmers, the confining boundaries and the fluid flow. I will discuss how this computational method can be modified to look at the dynamics in moving or heterogenous surroundings which aim to approximate the naturals habitats of such swimmers. The similarities and differences between the behavior of micro-swimmers such as bacteria, algae and spermatozoa will be noted.