Collective motion in a sheet of microswimmers
(2024) In Communications Physics 7(1).- Abstract
Self-propelled particles such as bacteria or algae swimming through a fluid are non-equilibrium systems where particle motility breaks microscopic detailed balance, often resulting in large-scale collective motion. Previous theoretical work has identified long-ranged hydrodynamic interactions as the driver of collective motion in unbounded suspensions of rear-actuated (“pusher”) microswimmers. In contrast, most experimental studies of collective motion in microswimmer suspensions have been carried out in restricted geometries where both the swimmers’ motion and their long-range flow fields become altered due to the proximity of a boundary. Here, we study numerically a minimal model of microswimmers in such a restricted geometry, where... (More)
Self-propelled particles such as bacteria or algae swimming through a fluid are non-equilibrium systems where particle motility breaks microscopic detailed balance, often resulting in large-scale collective motion. Previous theoretical work has identified long-ranged hydrodynamic interactions as the driver of collective motion in unbounded suspensions of rear-actuated (“pusher”) microswimmers. In contrast, most experimental studies of collective motion in microswimmer suspensions have been carried out in restricted geometries where both the swimmers’ motion and their long-range flow fields become altered due to the proximity of a boundary. Here, we study numerically a minimal model of microswimmers in such a restricted geometry, where the particles move in the midplane between two no-slip walls. For pushers, we demonstrate collective motion with short-ranged order, in contrast with the long-ranged flows observed in unbounded systems. For front-actuated (“puller”) microswimmers, we discover a long-wavelength density instability resulting in the formation of dense microswimmer clusters. Both types of collective motion are fundamentally different from their previously studied counterparts in unbounded domains. Our results show that this difference is dictated by the geometrical restriction of the swimmers’ motion, while hydrodynamic screening due to the presence of a wall is subdominant in determining the suspension’s collective state.
(Less)
- author
- Bárdfalvy, Dóra LU ; Škultéty, Viktor ; Nardini, Cesare ; Morozov, Alexander and Stenhammar, Joakim LU
- organization
- publishing date
- 2024-12
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Communications Physics
- volume
- 7
- issue
- 1
- article number
- 93
- publisher
- Nature Publishing Group
- external identifiers
-
- scopus:85187780674
- ISSN
- 2399-3650
- DOI
- 10.1038/s42005-024-01587-9
- language
- English
- LU publication?
- yes
- id
- 5876ea31-f915-4533-8eae-53b109e164e4
- date added to LUP
- 2024-04-03 13:13:53
- date last changed
- 2024-04-03 13:15:07
@article{5876ea31-f915-4533-8eae-53b109e164e4,
abstract = {{<p>Self-propelled particles such as bacteria or algae swimming through a fluid are non-equilibrium systems where particle motility breaks microscopic detailed balance, often resulting in large-scale collective motion. Previous theoretical work has identified long-ranged hydrodynamic interactions as the driver of collective motion in unbounded suspensions of rear-actuated (“pusher”) microswimmers. In contrast, most experimental studies of collective motion in microswimmer suspensions have been carried out in restricted geometries where both the swimmers’ motion and their long-range flow fields become altered due to the proximity of a boundary. Here, we study numerically a minimal model of microswimmers in such a restricted geometry, where the particles move in the midplane between two no-slip walls. For pushers, we demonstrate collective motion with short-ranged order, in contrast with the long-ranged flows observed in unbounded systems. For front-actuated (“puller”) microswimmers, we discover a long-wavelength density instability resulting in the formation of dense microswimmer clusters. Both types of collective motion are fundamentally different from their previously studied counterparts in unbounded domains. Our results show that this difference is dictated by the geometrical restriction of the swimmers’ motion, while hydrodynamic screening due to the presence of a wall is subdominant in determining the suspension’s collective state.</p>}},
author = {{Bárdfalvy, Dóra and Škultéty, Viktor and Nardini, Cesare and Morozov, Alexander and Stenhammar, Joakim}},
issn = {{2399-3650}},
language = {{eng}},
number = {{1}},
publisher = {{Nature Publishing Group}},
series = {{Communications Physics}},
title = {{Collective motion in a sheet of microswimmers}},
url = {{http://dx.doi.org/10.1038/s42005-024-01587-9}},
doi = {{10.1038/s42005-024-01587-9}},
volume = {{7}},
year = {{2024}},
}