Berlin 2024 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 6: Bacterial Biophysics I

BP 6.10: Vortrag

Montag, 18. März 2024, 17:45–18:00, H 1028

Bacteria in shear flow — •Pierre Martin¹, Tapan Chandra Adhyapak², and Holger Stark¹ — ¹Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany — ²Indian Institute of Science Education and Research (IISER), Tirupati, India

This study aims to investigate the behavior of flagellated bacteria under shear flow conditions, focusing on the specific case of E. coli bacteria. E. coli employs a rotating bundle of helical flagella for self-propulsion, and its ability to alter direction is facilitated by the reversal of flagellar rotation, a process known as tumbling.

In the presence of shear flow, helical objects, experience a chirality-induced drift force propelling them in the direction of vorticity. Additionally, objects in shear flow exhibit the well-known Jeffery orbit causing them to rotate. However, due to the helical bundle driving a non-chiral head, E. coli experiences a rheotactic torque and aligns along the vorticity axis. A phenomena known as rheotaxis.

To gain insights into these phenomena, we conducted a detailed analysis using a realistic model of E. coli coupled with fluid flow at low Reynolds numbers. The fluid flow was simulated using the method of multi-particle collision dynamics and Lees-Edwards boundary conditions were implemented to reproduce a planar shear flow in bulk.

Our research contributes to a deeper understanding of the complex interplay between flagellated bacteria and shear flow, shedding light on the responses of E. coli in such environments.

Keywords: Microswimmer; Numerical simulation; Hydrodynamic