(289g) Effects of Elasticity and Hydrodynamic Interactions on Swimmer Shape and Trajectories in a Coarse-Grained Model of Monotrichous Bacteria

The locomotion of singly-flagellated (monotrichous) bacteria in viscous fluid is a quintessential example of movement at low Reynolds number. Observations of such organisms have shown that both the hook protein (connecting cell body and flagellum) and the flagellum itself may buckle when a critical flexibility is exceeded, relative to the swimmer's generated propulsion. The former result is demonstrated with a simple linked rigid swimmer. The latter phenomena is considered at varying levels of description. First, we consider the elastic stability of a pinned flagellum in three separate cases with different dynamics and equilibrium shape, finding in each case that the flagellum indeed buckles above a critical flexibility. Next, we consider the case of an elastic flagellum pushing a cell body, examining the resultant trajectories and flow fields. Relatively rigid flagella produce similar results to the linked rigid swimmer, but very flexible flagella render propulsion ineffective post-buckling. These considerations may provide insight on how swimmers move through complex environments and how to expand potential application.