Howard Stone, Professor of Mechanical and Aerospace Engineering at Princeton University will be giving a lecture entitled: “Title: Bacteria, Biofilms and Fluid Dynamics: Elementary Flows and Unexpected Phenomena” as part of the Albert Kobayashi and Jim Morrison Lecture Series.
Bacterial biofilms have an enormous impact on medicine, industry and ecology. These microbial communities are generally considered to adhere to surfaces or interfaces. In most practical situations, the biofilms are exposed to flow. We investigate two features of such systems: (i) We examine the migration of bacteria along surfaces when exposed to a shear flow. In particular, we identify an unusual response where flow produces a directed motion of twitching bacteria in the upstream direction. (ii) We report the formation of biofilm streamers (threads of biofilm) suspended in the middle plane of curved micro channels under conditions of laminar flow. We use numerical simulations of the three-dimensional flow in curved channels to highlight the presence of a secondary vortical motion in the proximity of the corners, which suggests an underlying hydrodynamic mechanism responsible for the formation of the streamers. Thus, we bring together experiments, simulations, and models for the fluid-structure interaction to rationalize the spatial and temporal development of bacterial streamers.