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Schiltz-Rouse E, Row H, Mallory SA. Kinetic temperature and pressure of an active Tonks gas. Phys Rev E 2023; 108:064601. [PMID: 38243499 DOI: 10.1103/physreve.108.064601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 11/06/2023] [Indexed: 01/21/2024]
Abstract
Using computer simulation and analytical theory, we study an active analog of the well-known Tonks gas, where active Brownian particles are confined to a periodic one-dimensional (1D) channel. By introducing the notion of a kinetic temperature, we derive an accurate analytical expression for the pressure and clarify the paradoxical behavior where active Brownian particles confined to 1D exhibit anomalous clustering but no motility-induced phase transition. More generally, this work provides a deeper understanding of pressure in active systems as we uncover a unique link between the kinetic temperature and swim pressure valid for active Brownian particles in higher dimensions.
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Affiliation(s)
- Elijah Schiltz-Rouse
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Hyeongjoo Row
- Department of Chemical and Biomolecular Engineering, UC Berkeley, Berkeley, California 94720, USA
| | - Stewart A Mallory
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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van der Wee EB, Blackwell BC, Balboa Usabiaga F, Sokolov A, Katz IT, Delmotte B, Driscoll MM. A simple catch: Fluctuations enable hydrodynamic trapping of microrollers by obstacles. SCIENCE ADVANCES 2023; 9:eade0320. [PMID: 36888698 PMCID: PMC9995068 DOI: 10.1126/sciadv.ade0320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
It is known that obstacles can hydrodynamically trap bacteria and synthetic microswimmers in orbits, where the trapping time heavily depends on the swimmer flow field and noise is needed to escape the trap. Here, we use experiments and simulations to investigate the trapping of microrollers by obstacles. Microrollers are rotating particles close to a bottom surface, which have a prescribed propulsion direction imposed by an external rotating magnetic field. The flow field that drives their motion is quite different from previously studied swimmers. We found that the trapping time can be controlled by modifying the obstacle size or the colloid-obstacle repulsive potential. We detail the mechanisms of the trapping and find two remarkable features: The microroller is confined in the wake of the obstacle, and it can only enter the trap with Brownian motion. While noise is usually needed to escape traps in dynamical systems, here, we show that it is the only means to reach the hydrodynamic attractor.
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Affiliation(s)
- Ernest B. van der Wee
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
| | - Brendan C. Blackwell
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
| | | | - Andrey Sokolov
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Isaiah T. Katz
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
| | - Blaise Delmotte
- LadHyX, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau 91120, France
| | - Michelle M. Driscoll
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
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Ishimoto K, Gaffney EA, Smith DJ. Squirmer hydrodynamics near a periodic surface topography. Front Cell Dev Biol 2023; 11:1123446. [PMID: 37123410 PMCID: PMC10133482 DOI: 10.3389/fcell.2023.1123446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 03/15/2023] [Indexed: 05/02/2023] Open
Abstract
The behaviour of microscopic swimmers has previously been explored near large-scale confining geometries and in the presence of very small-scale surface roughness. Here, we consider an intermediate case of how a simple microswimmer, the tangential spherical squirmer, behaves adjacent to singly and doubly periodic sinusoidal surface topographies that spatially oscillate with an amplitude that is an order of magnitude less than the swimmer size and wavelengths that are also within an order of magnitude of this scale. The nearest neighbour regularised Stokeslet method is used for numerical explorations after validating its accuracy for a spherical tangential squirmer that swims stably near a flat surface. The same squirmer is then introduced to different surface topographies. The key governing factor in the resulting swimming behaviour is the size of the squirmer relative to the surface topography wavelength. For instance, directional guidance is not observed when the squirmer is much larger, or much smaller, than the surface topography wavelength. In contrast, once the squirmer size is on the scale of the topography wavelength, limited guidance is possible, often with local capture in the topography troughs. However, complex dynamics can also emerge, especially when the initial configuration is not close to alignment along topography troughs or above topography crests. In contrast to sensitivity in alignment and topography wavelength, reductions in the amplitude of the surface topography or variations in the shape of the periodic surface topography do not have extensive impacts on the squirmer behaviour. Our findings more generally highlight that the numerical framework provides an essential basis to elucidate how swimmers may be guided by surface topography.
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Affiliation(s)
- Kenta Ishimoto
- Research Institute for Mathematical Sciences, Kyoto University, Kyoto, Japan
- *Correspondence: Kenta Ishimoto,
| | - Eamonn A. Gaffney
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom
| | - David J. Smith
- School of Mathematics, University of Birmingham, Birmingham, United Kingdom
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Kaiser M, Kantorovich SS. The importance of being a cube: Active cubes in a microchannel. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Gandikota MC, Cacciuto A. Effective forces between active polymers. Phys Rev E 2022; 105:034503. [PMID: 35428068 DOI: 10.1103/physreve.105.034503] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 03/01/2022] [Indexed: 06/14/2023]
Abstract
The characterization of the interactions between two fully flexible self-avoiding polymers is one of the classic and most important problems in polymer physics. In this paper we measure these interactions in the presence of active fluctuations. We introduce activity into the problem using two of the most popular models in this field, one where activity is effectively embedded into the monomers' dynamics, and the other where passive polymers fluctuate in an explicit bath of active particles. We establish the conditions under which the interaction between active polymers can be mapped into the classical passive problem. We observe that the active bath can drive the development of strong attractive interactions between the polymers and that, upon enforcing a significant degree of overlap, they come together to form a single double-stranded unit. A phase diagram tracing this change in conformational behavior is also reported.
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Affiliation(s)
- M C Gandikota
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
| | - A Cacciuto
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
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Clopés Llahí J, Martín-Gómez A, Gompper G, Winkler RG. Simulating wet active polymers by multiparticle collision dynamics. Phys Rev E 2022; 105:015310. [PMID: 35193189 DOI: 10.1103/physreve.105.015310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 01/05/2022] [Indexed: 06/14/2023]
Abstract
The conformational and dynamical properties of active Brownian polymers embedded in a fluid depend on the nature of the driving mechanism, e.g., self-propulsion or external actuation of the monomers. Implementations of self-propelled and actuated active Brownian polymers in a multiparticle collision (MPC) dynamics fluid are presented, which capture the distinct differences between the two driving mechanisms. The active force-free nature of self-propelled monomers requires adaptations of the MPC simulation scheme, with its streaming and collision steps, where the monomer self-propulsion velocity has to be omitted in the collision step. Comparison of MPC simulation results for active polymers in dilute solution with results of Brownian dynamics simulations accounting for hydrodynamics via the Rotne-Prager-Yamakawa tensor confirm the suitability of the implementation. The polymer conformational and dynamical properties are analyzed by the static and dynamic structure factor, and the scaling behavior of the latter with respect to the wave number and time dependence are discussed. The dynamic structure factor displays various activity-induced temporal regimes, depending on the considered wave number, which reflect the persistent diffusive motion of the whole polymer at small wave numbers, and the activity-enhanced internal dynamics at large wave numbers. The obtained simulation results are compared with theoretical predictions.
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Affiliation(s)
- Judit Clopés Llahí
- Theoretical Physics of Living Matter, Institute of Biological Information Processing and Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Aitor Martín-Gómez
- Theoretical Physics of Living Matter, Institute of Biological Information Processing and Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Gerhard Gompper
- Theoretical Physics of Living Matter, Institute of Biological Information Processing and Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Roland G Winkler
- Theoretical Physics of Living Matter, Institute of Biological Information Processing and Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany
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Purushothaman A, Thampi SP. Hydrodynamic collision between a microswimmer and a passive particle in a micro-channel. SOFT MATTER 2021; 17:3380-3396. [PMID: 33644792 DOI: 10.1039/d0sm02140g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Microswimmers interacting with passive particles in confinement are common in many systems, e.g., spermatozoa encountering other cells or debris in the female reproductive tract or active particles interacting with polymers and tracers in microfluidic channels. The behaviour of such systems is driven by simultaneous, three way hydrodynamic interactions between the microswimmer, the passive particle and the microchannel walls. Therefore, in this work we investigate the hydrodynamic collision between a model microswimmer and a passive particle using three different methods: (i) the point particle approach, (ii) analytical calculations based on method of reflections, and (iii) lattice Boltzmann numerical simulations. We show that the hydrodynamic collision is essentially an asymmetric process - the trajectory of the microswimmer is altered only in an intermediate stage while the passive particle undergoes a three stage displacement with a net displacement towards or away from the microchannel walls. The path of the passive particle is a simple consequence of the velocity field generated by the swimmer: an open triangle in bulk fluid and a loop-like trajectory in confinement. We demonstrate the generality of our findings and conclude that the net displacement of the passive particle due to collision may be capitalised in order to develop applications such as size separation of colloidal particles and deposition of particles in the microchannel interiors.
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Affiliation(s)
- Ahana Purushothaman
- Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
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Narinder N, Zhu WJ, Bechinger C. Active colloids under geometrical constraints in viscoelastic media. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:28. [PMID: 33704591 PMCID: PMC7952293 DOI: 10.1140/epje/s10189-021-00033-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/29/2021] [Indexed: 05/26/2023]
Abstract
We study the behavior of active particles (APs) moving in a viscoelastic fluid in the presence of geometrical confinements. Upon approaching a flat wall, we find that APs slow down due to compression of the enclosed viscoelastic fluid. In addition, they receive a viscoelastic torque leading to sudden orientational changes and departure from walls. Based on these observations, we develop a numerical model which can also be applied to other geometries and yields good agreement with experimental data. Our results demonstrate, that APs are able to move through complex geometrical structures more effectively when suspended in a viscoelastic compared to a Newtonian fluid.
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Affiliation(s)
- N Narinder
- Fachbereich Physik, Universität Konstanz, Konstanz, Germany
| | - Wei-Jing Zhu
- Fachbereich Physik, Universität Konstanz, Konstanz, Germany
- School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, China
- School of Photoelectric Engineering, Guangdong Polytechnic Normal University, Guangzhou, 510665, China
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