Presented by Enkeleida Lushi, from Simons Foundation Flatiron Institute.

Abstract

Nature is full of collective patterns that emerge from the behavior of individual organisms. Microscopic swimming cells such as bacteria, algae, and spermatozoa exhibit these kinds of coordinated patterns as well. The intricate dynamics of micro-swimmers seen in the lab is shown to result from a complex interplay of the individuals interacting with each other, the surrounding fluid and the environment. I will present simulations that resolve these interactions, and look at the dynamics of swimmers in circular drops, racetracks or moving domains. Experiments with Bacillus Subtilis bacteria confirm the predictions of a stable swirling vortex in circular drops or a persistent unidirectional stream in racetracks. The similarities and differences between the behavior of bacteria, algae and spermatozoa will be discussed. This work helps our understanding of how bacteria spread in their natural environment. It could also aid in the development of medical devices with surfaces and architectures that can manipulate bacterial movements and spread.