SKM 2023 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 6: Bacterial Mechanics
BP 6.2: Vortrag
Montag, 27. März 2023, 15:15–15:30, BAR 0106
Stress anisotropy in confined populations of growing rods — Jonas Isensee1,2, Lukas Hupe1,2, Ramin Golestanian1,2,3, and •Philip Bittihn1,2 — 1Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany — 2Institute for the Dynamics of Complex Systems, Göttingen University — 3Rudolf Peierls Centre for Theoretical Physics, University of Oxford, UK
A central feature of living matter is its ability to grow and multiply. The mechanical activity associated with growth produces both macroscopic flows shaped by confinement, and striking self-organization phenomena, such as orientational order and alignment, which are particularly prominent in populations of rod-shaped bacteria due to their nematic properties. However, how active stresses, passive mechanical interactions and flow-induced effects interact to give rise to global alignment patterns remains elusive. Here, we study in silico colonies of growing rod-shaped particles confined in channel-like geometries. A spatially resolved analysis of the stress tensor reveals a strong relationship between near-perfect alignment and an inversion of stress anisotropy for particles with large length-to-width ratios. In quantitative agreement with an asymptotic theory, strong alignment can lead to a decoupling of active and passive stresses parallel and perpendicular to the growth axis, respectively. We demonstrate the robustness of these effects to perturbations and for weaker confinement. Our results illustrate the complexity arising from the inherent coupling between nematic order and active stresses in growing active matter, modulated by geometric and configurational constraints due to confinement.