Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids
We show that an inclusion placed inside a dilute Stokesian suspension of microswimmers induces power-law number-density modulations and flows. These take a different form depending on whether the inclusion is held fixed by an external force—for example, an optical tweezer—or if it is free. When the...
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| Format: | Article |
| Language: | English |
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American Physical Society
2024-11-01
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| Series: | Physical Review X |
| Online Access: | http://doi.org/10.1103/PhysRevX.14.041034 |
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| author | Thibaut Arnoulx de Pirey Yariv Kafri Sriram Ramaswamy |
| author_facet | Thibaut Arnoulx de Pirey Yariv Kafri Sriram Ramaswamy |
| author_sort | Thibaut Arnoulx de Pirey |
| collection | DOAJ |
| description | We show that an inclusion placed inside a dilute Stokesian suspension of microswimmers induces power-law number-density modulations and flows. These take a different form depending on whether the inclusion is held fixed by an external force—for example, an optical tweezer—or if it is free. When the inclusion is held in place, the far-field fluid flow is a Stokeslet, while the microswimmer density decays as 1/r^{2+ε}, with r the distance from the inclusion and ε an anomalous exponent which depends on the symmetry of the inclusion and varies continuously as a function of a dimensionless number characterizing the relative amplitudes of the convective and diffusive effects. The angular dependence takes a nontrivial form which depends on the same dimensionless number. When the inclusion is free to move, the far-field fluid flow is a stresslet, and the microswimmer density decays as 1/r^{2} with a simple angular dependence. These long-range modulations mediate long-range interactions between inclusions that we characterize. |
| format | Article |
| id | doaj-art-e12f9f487f8149d1b1a5651cc9ab5c75 |
| institution | OA Journals |
| issn | 2160-3308 |
| language | English |
| publishDate | 2024-11-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review X |
| spelling | doaj-art-e12f9f487f8149d1b1a5651cc9ab5c752025-08-20T02:12:34ZengAmerican Physical SocietyPhysical Review X2160-33082024-11-0114404103410.1103/PhysRevX.14.041034Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active FluidsThibaut Arnoulx de PireyYariv KafriSriram RamaswamyWe show that an inclusion placed inside a dilute Stokesian suspension of microswimmers induces power-law number-density modulations and flows. These take a different form depending on whether the inclusion is held fixed by an external force—for example, an optical tweezer—or if it is free. When the inclusion is held in place, the far-field fluid flow is a Stokeslet, while the microswimmer density decays as 1/r^{2+ε}, with r the distance from the inclusion and ε an anomalous exponent which depends on the symmetry of the inclusion and varies continuously as a function of a dimensionless number characterizing the relative amplitudes of the convective and diffusive effects. The angular dependence takes a nontrivial form which depends on the same dimensionless number. When the inclusion is free to move, the far-field fluid flow is a stresslet, and the microswimmer density decays as 1/r^{2} with a simple angular dependence. These long-range modulations mediate long-range interactions between inclusions that we characterize.http://doi.org/10.1103/PhysRevX.14.041034 |
| spellingShingle | Thibaut Arnoulx de Pirey Yariv Kafri Sriram Ramaswamy Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids Physical Review X |
| title | Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids |
| title_full | Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids |
| title_fullStr | Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids |
| title_full_unstemmed | Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids |
| title_short | Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids |
| title_sort | anomalous long ranged influence of an inclusion in momentum conserving active fluids |
| url | http://doi.org/10.1103/PhysRevX.14.041034 |
| work_keys_str_mv | AT thibautarnoulxdepirey anomalouslongrangedinfluenceofaninclusioninmomentumconservingactivefluids AT yarivkafri anomalouslongrangedinfluenceofaninclusioninmomentumconservingactivefluids AT sriramramaswamy anomalouslongrangedinfluenceofaninclusioninmomentumconservingactivefluids |