Collective motion in a sheet of microswimmers
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 interactio...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2024-03-01
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| Series: | Communications Physics |
| Online Access: | https://doi.org/10.1038/s42005-024-01587-9 |
| _version_ | 1797259197781377024 |
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| author | Dóra Bárdfalvy Viktor Škultéty Cesare Nardini Alexander Morozov Joakim Stenhammar |
| author_facet | Dóra Bárdfalvy Viktor Škultéty Cesare Nardini Alexander Morozov Joakim Stenhammar |
| author_sort | Dóra Bárdfalvy |
| collection | DOAJ |
| description | 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 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. |
| first_indexed | 2024-04-24T23:05:36Z |
| format | Article |
| id | doaj.art-20b488b53ecc4b668571a22ff5d77944 |
| institution | Directory Open Access Journal |
| issn | 2399-3650 |
| language | English |
| last_indexed | 2024-04-24T23:05:36Z |
| publishDate | 2024-03-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Communications Physics |
| spelling | doaj.art-20b488b53ecc4b668571a22ff5d779442024-03-17T12:28:29ZengNature PortfolioCommunications Physics2399-36502024-03-01711810.1038/s42005-024-01587-9Collective motion in a sheet of microswimmersDóra Bárdfalvy0Viktor Škultéty1Cesare Nardini2Alexander Morozov3Joakim Stenhammar4Division of Physical Chemistry, Lund UniversitySUPA, School of Physics and Astronomy, The University of EdinburghService de Physique de l’État Condensé, CNRS UMR 3680, CEA-SaclaySUPA, School of Physics and Astronomy, The University of EdinburghDivision of Physical Chemistry, Lund UniversityAbstract 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.https://doi.org/10.1038/s42005-024-01587-9 |
| spellingShingle | Dóra Bárdfalvy Viktor Škultéty Cesare Nardini Alexander Morozov Joakim Stenhammar Collective motion in a sheet of microswimmers Communications Physics |
| title | Collective motion in a sheet of microswimmers |
| title_full | Collective motion in a sheet of microswimmers |
| title_fullStr | Collective motion in a sheet of microswimmers |
| title_full_unstemmed | Collective motion in a sheet of microswimmers |
| title_short | Collective motion in a sheet of microswimmers |
| title_sort | collective motion in a sheet of microswimmers |
| url | https://doi.org/10.1038/s42005-024-01587-9 |
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