1
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Isele M, Hofmann K, Erbe A, Leiderer P, Nielaba P. Lane formation of colloidal particles driven in parallel by gravity. Phys Rev E 2023; 108:034607. [PMID: 37849083 DOI: 10.1103/physreve.108.034607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/28/2023] [Indexed: 10/19/2023]
Abstract
We investigate the lane formation in nonequilibrium systems of colloidal particles moving in parallel that are driven by the force of gravity. For this setup, an experimental implementation of a channel on a slope can be conceptualized. We employ the Brownian dynamics algorithm and confine the repulsive particles with hard walls based on the solution of the Smoluchowski equation in the half space. A difference of the driving force acting on the colloids could be achieved by using two spherical particle types with differing diameters but equal mass density. First, we investigate how a difference in the channel slope affects the lane formation of the systems, after which we analyze the lanes that formed. We find that the large particles push the small particles to the walls, resulting in exclusively small particle lanes at the walls. This contrasts the equilibrium state, where depletion forces push the larger particles to the walls. Additionally, we have a closer look at the mechanisms by which the lanes form. Finally, we find system parameter values that foster lane formation to lay the foundation for an experimental realization of our proposed setup. To round this off, we give an exemplary calculation of the slope angle needed to get the experimental system into a state of lane order. With the examination of lane order in systems that are driven in parallel, we hope to deepen our understanding of nonequilibrium order phenomena.
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Affiliation(s)
- Marc Isele
- Physics Department, University of Konstanz, 78457 Konstanz, Germany
| | - Kay Hofmann
- Physics Department, University of Konstanz, 78457 Konstanz, Germany
| | - Artur Erbe
- Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Paul Leiderer
- Physics Department, University of Konstanz, 78457 Konstanz, Germany
| | - Peter Nielaba
- Physics Department, University of Konstanz, 78457 Konstanz, Germany
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2
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Caprini L, Löwen H. Flocking without Alignment Interactions in Attractive Active Brownian Particles. PHYSICAL REVIEW LETTERS 2023; 130:148202. [PMID: 37084461 DOI: 10.1103/physrevlett.130.148202] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 03/13/2023] [Indexed: 05/03/2023]
Abstract
Within a simple model of attractive active Brownian particles, we predict flocking behavior and challenge the widespread idea that alignment interactions are necessary to observe this collective phenomenon. Here, we show that even nonaligning attractive interactions can lead to a flocking state. Monitoring the velocity polarization as the order parameter, we reveal the onset of a first-order transition from a disordered phase, characterized by several small clusters, to a flocking phase, where a single flocking cluster is emerging. The scenario is confirmed by studying the spatial connected correlation function of particle velocities, which reveals scale-free behavior in flocking states and exponential-like decay for nonflocking configurations. Our predictions can be tested in microscopic and macroscopic experiments showing flocking, such as animals, migrating cells, and active colloids.
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Affiliation(s)
- L Caprini
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - H Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
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3
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Qian D, Olvera de la Cruz M. Field-driven cluster formation in two-dimensional colloidal binary mixtures. Phys Rev E 2023; 107:044605. [PMID: 37198853 DOI: 10.1103/physreve.107.044605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 03/22/2023] [Indexed: 05/19/2023]
Abstract
We study size- and charge-asymmetric oppositely charged colloids driven by an external electric field. The large particles are connected by harmonic springs, forming a hexagonal-lattice network, while the small particles are free of bonds and exhibit fluidlike motion. We show that this model exhibits a cluster formation pattern when the external driving force exceeds a critical value. The clustering is accompanied with stable wave packets in vibrational motions of the large particles.
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Affiliation(s)
- Dingwen Qian
- Applied Physics Program, Northwestern University, Evanston, Illinois 60208, USA
| | - Monica Olvera de la Cruz
- Applied Physics Program, Department of Materials Science and Engineering, Department of Chemistry, and Department of Physic and Astronomy, Northwestern University, Evanston, Illinois 60208, USA
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4
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Hrishikesh B, Mani E. Collective behavior of passive and active circle swimming particle mixtures. SOFT MATTER 2023; 19:225-232. [PMID: 36510815 DOI: 10.1039/d2sm01066f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We present a numerical study on a binary mixture of passive and circle swimming, self-propelling particles which interact via the Lennard-Jones (LJ) potential in two dimensions. Using Brownian Dynamics (BD) simulations, we present state diagrams using the control parameters such as attraction strength, angular velocity, self-propulsion velocity and composition. In a symmetric mixture, the system undergoes a transition from a mixed gel to a rotating passive cluster state and finally to a homogeneous fluid state as translational activity increases. The formation of the rotating cluster of passive particles surrounded by active and passive monomers is attributed to the combined effect of composition, activity and strength of attraction of the active particles. Different phases are characterized using radial distribution functions, bond order parameters, cluster fraction and probability distribution of local volume fractions. The present study addresses comprehensively the intricate role of activity, angular velocity, inter-particle interaction and compositional variation on the phase behavior. The predictions presented in the study can be experimentally realized in synthetic colloidal swimmers and motile bacterial suspensions.
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Affiliation(s)
- Bhadra Hrishikesh
- Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, 600 036, Tamil Nadu, India.
| | - Ethayaraja Mani
- Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, 600 036, Tamil Nadu, India.
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5
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Yu H, Thijssen K, Jack RL. Perpendicular and parallel phase separation in two-species driven diffusive lattice gases. Phys Rev E 2022; 106:024129. [PMID: 36110007 DOI: 10.1103/physreve.106.024129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 08/01/2022] [Indexed: 06/15/2023]
Abstract
We study three different lattice models in which two species of diffusing particles are driven in opposite directions by an electric field. We focus on dynamical phase transitions that involve phase separation into domains that may be parallel or perpendicular to a driving field. In all cases, the perpendicular state appears for weak driving, consistent with previous work. For strong driving, we introduce two models that support the parallel state. In one model, this state occurs because of the inclusion of dynamical rules that enhance lateral diffusion during collisions; in the other, it is a result of a nearest-neighbor attractive or repulsive interaction between particles of the same or opposite species. We discuss the connections between these results and the behavior found in off-lattice systems, including laning and freezing by heating.
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Affiliation(s)
- Honghao Yu
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Kristian Thijssen
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Robert L Jack
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
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6
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Sesé-Sansa E, Liao GJ, Levis D, Pagonabarraga I, Klapp SHL. Impact of dipole-dipole interactions on motility-induced phase separation. SOFT MATTER 2022; 18:5388-5401. [PMID: 35797661 DOI: 10.1039/d2sm00385f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We present a hydrodynamic theory for systems of dipolar active Brownian particles which, in the regime of weak dipolar coupling, predicts the onset of motility-induced phase separation (MIPS), consistent with Brownian dynamics (BD) simulations. The hydrodynamic equations are derived by explicitly coarse-graining the microscopic Langevin dynamics, thus allowing for a mapping of the coarse-grained model and particle-resolved simulations. Performing BD simulations at fixed density, we find that dipolar interactions tend to hinder MIPS, as first reported in [Liao et al., Soft Matter, 2020, 16, 2208]. Here we demonstrate that the theoretical approach indeed captures the suppression of MIPS. Moreover, the analysis of the numerically obtained, angle-dependent correlation functions sheds light into the underlying microscopic mechanisms leading to the destabilization of the homogeneous phase.
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Affiliation(s)
- Elena Sesé-Sansa
- CECAM, Centre Européen de Calcul Atomique et Moléculaire, École Polytechnique Fédérale de Lausanne (EPFL), Batochime, Avenue Forel 2, 1015 Lausanne, Switzerland.
| | - Guo-Jun Liao
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany
| | - Demian Levis
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès 1, E08028 Barcelona, Spain
- UBICS University of Barcelona Institute of Complex Systems, Martí i Franquès 1, E08028 Barcelona, Spain
| | - Ignacio Pagonabarraga
- CECAM, Centre Européen de Calcul Atomique et Moléculaire, École Polytechnique Fédérale de Lausanne (EPFL), Batochime, Avenue Forel 2, 1015 Lausanne, Switzerland.
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès 1, E08028 Barcelona, Spain
- UBICS University of Barcelona Institute of Complex Systems, Martí i Franquès 1, E08028 Barcelona, Spain
| | - Sabine H L Klapp
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany
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7
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Bickmann J, Bröker S, Jeggle J, Wittkowski R. Analytical approach to chiral active systems: suppressed phase separation of interacting Brownian circle swimmers. J Chem Phys 2022; 156:194904. [DOI: 10.1063/5.0085122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We consider chirality in active systems by exemplarily studying the phase behavior of planar systems of interacting Brownian circle swimmers with a spherical shape. For this purpose, we derive a predictive field theory that is able to describe the collective dynamics of circle swimmers. The theory yields a mapping between circle swimmers and noncircling active Brownian particles and predicts that the angular propulsion of the particles leads to a suppression of their motility-induced phase separation, being in line with recent simulation results. In addition, the theory provides analytical expressions for the spinodal corresponding to the onset of motility-induced phase separation and the associated critical point as well as for their dependence on the angular propulsion of the circle swimmers. We confirm our findings by Brownian dynamics simulations. The agreement between results from theory and simulations is found to be good.
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Affiliation(s)
- Jens Bickmann
- Westfälische Wilhelms-Universität Münster Fachbereich 11 Physik, Germany
| | - Stephan Bröker
- Westfälische Wilhelms-Universität Münster Fachbereich 11 Physik, Germany
| | - Julian Jeggle
- Westfälische Wilhelms-Universität Münster Fachbereich 11 Physik, Germany
| | - Raphael Wittkowski
- Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster Fachbereich 11 Physik, Germany
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8
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Samsuzzaman M, Sayeed A, Saha A. Reentrant melting of lanes of rough circular disks. Phys Rev E 2022; 105:024608. [PMID: 35291112 DOI: 10.1103/physreve.105.024608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 02/04/2022] [Indexed: 06/14/2023]
Abstract
We consider binary suspension of rough, circular particles in two dimensions under athermal conditions. The suspension is subject to a time-independent external drive in response to which half of the particles are pulled along the field direction, whereas the other half is pushed in the opposite direction. Simulating the system with different magnitude of external drive in steady state, we obtain oppositely moving macroscopic lanes only for a moderate range of external drive. Below as well as above the range we obtain states with no lane. Hence we find that the no-lane state reenters along the axis of the external drive in the nonequilibrium phase diagram corresponding to the laning transition, with varying roughness of individual particles and external drive. Interparticle friction (contact dissipation) due to the roughness of the individual particle is the main player behind the reentrance of the no-lane state at high external drives.
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Affiliation(s)
- Md Samsuzzaman
- Department of Physics, Savitribai Phule Pune University, Pune 411007, India
| | - Ahmed Sayeed
- Department of Physics, Savitribai Phule Pune University, Pune 411007, India
| | - Arnab Saha
- Department of Physics, University Of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata-700009, India
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9
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Li B, Wang YL, Shi G, Gao Y, Shi X, Woodward CE, Forsman J. Phase Transitions of Oppositely Charged Colloidal Particles Driven by Alternating Current Electric Field. ACS NANO 2021; 15:2363-2373. [PMID: 33576616 PMCID: PMC8023798 DOI: 10.1021/acsnano.0c04095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We study systems containing oppositely charged colloidal particles under applied alternating current electric fields (AC fields) using overdamped Langevin dynamics simulations in three dimensions. We obtain jammed bands perpendicular to the field direction under intermediate frequencies and lanes parallel with the field under low frequencies. These structures also depend upon the particle charges. The pathway for generating jammed bands follows a stepwise mechanism, and intermediate bands are observed during lane formation in some systems. We investigate the component of the pressure tensors in the direction parallel to the field and observe that the jammed to lane transition occurs at a critical value for this pressure. We also find that the stable steady states appear to satisfy the principle of maximum entropy production. Our results may help to improve the understand of the underlying mechanisms for these types of dynamic phase transitions and the subsequent cooperative assemblies of colloidal particles under such non-equilibrium conditions.
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Affiliation(s)
- Bin Li
- Laboratory
of Theoretical and Computational Nanoscience, CAS Key Laboratory for
Nanosystem and Hierarchy Fabrication, CAS Center for Excellence in
Nanoscience, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, China
- Theoretical
Chemistry, Chemical Center, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
- School
of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, China
| | - Yong-Lei Wang
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Guang Shi
- Department
of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Yangyang Gao
- Key
Laboratory of Beijing City on Preparation and Processing of Novel
Polymer Materials, Beijing University of
Chemical Technology, Beijing 10029, China
- State Key
Laboratory of Organic−Inorganic Composites, Beijing University of Chemical Technology, Beijing 10029, China
| | - Xinghua Shi
- Laboratory
of Theoretical and Computational Nanoscience, CAS Key Laboratory for
Nanosystem and Hierarchy Fabrication, CAS Center for Excellence in
Nanoscience, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, China
| | - Clifford E. Woodward
- School
of Physical, Environmental and Mathematical Sciences, University College,
ADFA, University of New South Wales, Canberra, ACT 2600, Australia
| | - Jan Forsman
- Theoretical
Chemistry, Chemical Center, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
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10
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Sprenger AR, Shaik VA, Ardekani AM, Lisicki M, Mathijssen AJTM, Guzmán-Lastra F, Löwen H, Menzel AM, Daddi-Moussa-Ider A. Towards an analytical description of active microswimmers in clean and in surfactant-covered drops. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2020; 43:58. [PMID: 32920676 DOI: 10.1140/epje/i2020-11980-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/10/2020] [Indexed: 05/24/2023]
Abstract
Geometric confinements are frequently encountered in the biological world and strongly affect the stability, topology, and transport properties of active suspensions in viscous flow. Based on a far-field analytical model, the low-Reynolds-number locomotion of a self-propelled microswimmer moving inside a clean viscous drop or a drop covered with a homogeneously distributed surfactant, is theoretically examined. The interfacial viscous stresses induced by the surfactant are described by the well-established Boussinesq-Scriven constitutive rheological model. Moreover, the active agent is represented by a force dipole and the resulting fluid-mediated hydrodynamic couplings between the swimmer and the confining drop are investigated. We find that the presence of the surfactant significantly alters the dynamics of the encapsulated swimmer by enhancing its reorientation. Exact solutions for the velocity images for the Stokeslet and dipolar flow singularities inside the drop are introduced and expressed in terms of infinite series of harmonic components. Our results offer useful insights into guiding principles for the control of confined active matter systems and support the objective of utilizing synthetic microswimmers to drive drops for targeted drug delivery applications.
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Affiliation(s)
- Alexander R Sprenger
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225, Düsseldorf, Germany.
| | - Vaseem A Shaik
- School of Mechanical Engineering, Purdue University, 47907, West Lafayette, IN, USA
| | - Arezoo M Ardekani
- School of Mechanical Engineering, Purdue University, 47907, West Lafayette, IN, USA
| | - Maciej Lisicki
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | - Arnold J T M Mathijssen
- Department of Bioengineering, Stanford University, 443 Via Ortega, 94305, Stanford, CA, USA
- Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, 19104, Philadelphia, PA, USA
| | - Francisca Guzmán-Lastra
- Centro de Investigación DAiTA Lab, Facultad de Estudios Interdisciplinarios, Universidad Mayor, Av. Manuel Montt 367, Providencia, Santiago de Chile, Chile
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225, Düsseldorf, Germany
| | - Andreas M Menzel
- Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106, Magdeburg, Germany
| | - Abdallah Daddi-Moussa-Ider
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225, Düsseldorf, Germany
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11
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Maloney RC, Hall CK. Clustering and Phase Separation in Mixtures of Dipolar and Active Particles in an External Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6378-6387. [PMID: 32418424 DOI: 10.1021/acs.langmuir.0c00516] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Directing the assembly of colloidal particles through the use of external electric or magnetic fields shows promise for the creation of reconfigurable materials. Self-propelled particles can also be used to dynamically drive colloidal systems to nonequilibrium steady states. We investigate colloidal systems that combine both of these methods of directed assembly, simulating mixtures of passive dipolar colloids and active soft spheres in an external magnetic field using Brownian dynamics in two dimensions. In these systems, the dipolar particles align in the direction of the external field, but the active particles are unaffected by the field. The phase behaviors exhibited included a percolated dipolar network, dipolar string-fluid, isotropic fluid, and phase-separated state. We find that the external field allows the dipolar particles to form a percolated network more easily compared to when no external field is present. Additionally, the mixture phase separates at lower active particle velocity in an external field than when no field is present. Our results suggest that combining multiple methods of directing colloidal assembly could lead to new pathways to fabricate reconfigurable materials.
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Affiliation(s)
- Ryan C Maloney
- Department of Chemical Engineering, North Carolina State University, 911 Partners Way, Raleigh, North Carolina 27606, United States
| | - Carol K Hall
- Department of Chemical Engineering, North Carolina State University, 911 Partners Way, Raleigh, North Carolina 27606, United States
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12
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Maloney RC, Liao GJ, Klapp SHL, Hall CK. Clustering and phase separation in mixtures of dipolar and active particles. SOFT MATTER 2020; 16:3779-3791. [PMID: 32239046 DOI: 10.1039/c9sm02311a] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The self-assembly of colloidal particles in dynamic environments has become an important field of study because of potential applications in fabricating out-of-equilibrium materials. We investigate the phase behavior of mixtures of passive dipolar colloids and active soft spheres using Brownian dynamics simulations in two dimensions. The phase behaviors exhibited include dipolar percolated network, dipolar string-fluid, isotropic fluid, and a phase-separated state. We find that the clustering of dipolar colloids is enhanced in the presence of slow-moving active particles compared to the clustering of dipolar particles mixed with passive particles. When the active particle motility is high, the chains of dipolar particles are either broken into short chains or pushed into dense clusters. Motility-induced phase separation into dense and dilute phases is also present. The area fraction of particles in the dilute phase increases as the fraction of active particles in the system decreases, while the area fraction of particles in the dense phase remains constant. Our findings are relevant to the development of reconfigurable self-assembled materials.
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Affiliation(s)
- Ryan C Maloney
- Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA.
| | - Guo-Jun Liao
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, D10623 Berlin, Germany
| | - Sabine H L Klapp
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, D10623 Berlin, Germany
| | - Carol K Hall
- Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA.
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13
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Treffenstädt LL, Schmidt M. Memory-induced motion reversal in Brownian liquids. SOFT MATTER 2020; 16:1518-1526. [PMID: 31939985 DOI: 10.1039/c9sm02005e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We study the Brownian dynamics of hard spheres under spatially inhomogeneous shear, using event-driven Brownian dynamics simulations and power functional theory. We examine density and current profiles both for steady states and for the transient dynamics after switching on and switching off an external square wave shear force field. We find that a dense hard sphere fluid (volume fraction ≈0.35) undergoes global motion reversal after switching off the shear force field. We use power functional theory with a spatially nonlocal memory kernel to describe the superadiabatic force contributions and obtain good quantitative agreement of the theoretical results with simulation data. The theory provides an explanation for the motion reversal: internal superadiabatic nonequilibrium forces that oppose the externally driven current arise due to memory after switching off. The effect is genuinely viscoelastic: in steady state, viscous forces oppose the current, but they elastically generate an opposing current after switch-off.
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Affiliation(s)
- Lucas L Treffenstädt
- Theoretische Physik II, Universität Bayreuth, Universitätsstr. 30, D-95447 Bayreuth, Germany.
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14
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Reichhardt CJO, Reichhardt C. Disordering, clustering, and laning transitions in particle systems with dispersion in the Magnus term. Phys Rev E 2019; 99:012606. [PMID: 30780381 DOI: 10.1103/physreve.99.012606] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Indexed: 11/07/2022]
Abstract
We numerically examine a two-dimensional system of repulsively interacting particles with dynamics that are governed by both a damping term and a Magnus term. The magnitude of the Magnus term has one value for half of the particles and a different value for the other half of the particles. In the absence of a driving force, the particles form a triangular lattice, while when a driving force is applied, we find that there is a critical drive above which a Magnus-induced disordering transition can occur even if the difference in the Magnus term between the two particle species is as small as one percent. The transition arises due to the different Hall angles of the two species, which causes their motion to decouple at the critical drive. At higher drives, the disordered state can undergo both species and density phase separation into a density-modulated stripe that is oriented perpendicular to the driving direction. We observe several additional phases that occur as a function of drive and Magnus force disparity, including a variety of density-modulated diagonal-laned phases. In general, we find a much richer variety of states compared to systems of oppositely driven overdamped Yukawa particles. We discuss the implications of our work for skyrmion systems, where we predict that even for small skyrmion dispersities, a drive-induced disordering transition can occur along with clustering phases and pattern-forming states.
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Affiliation(s)
- C J O Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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15
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Liao GJ, Klapp SHL. Clustering and phase separation of circle swimmers dispersed in a monolayer. SOFT MATTER 2018; 14:7873-7882. [PMID: 30221296 DOI: 10.1039/c8sm01366g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We perform Brownian dynamics simulations in two dimensions to study the collective behavior of circle swimmers, which are driven by both, an (effective) translational and rotational self-propulsion, and interact via steric repulsion. We find that active rotation generally opposes motility-induced clustering and phase separation, as demonstrated by a narrowing of the coexistence region upon increase of the propulsion angular velocity. Moreover, although the particles are intrinsically assigned to rotate counterclockwise, a novel state of clockwise vortices emerges at an optimal value of the effective propulsion torque. We propose a simple gear-like model to capture the underlying mechanism of the clockwise vortices.
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Affiliation(s)
- Guo-Jun Liao
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany.
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16
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Stuhlmüller NCX, Eckert T, de Las Heras D, Schmidt M. Structural Nonequilibrium Forces in Driven Colloidal Systems. PHYSICAL REVIEW LETTERS 2018; 121:098002. [PMID: 30230856 DOI: 10.1103/physrevlett.121.098002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 07/13/2018] [Indexed: 06/08/2023]
Abstract
We identify a structural one-body force field that sustains spatial inhomogeneities in nonequilibrium overdamped Brownian many-body systems. The structural force is perpendicular to the local flow direction, it is free of viscous dissipation, it is microscopically resolved in both space and time, and it can stabilize density gradients. From the time evolution in the exact (Smoluchowski) low-density limit, Brownian dynamics simulations, and a novel power functional approximation, we obtain a quantitative understanding of viscous and structural forces, including memory and shear migration.
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Affiliation(s)
- Nico C X Stuhlmüller
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
| | - Tobias Eckert
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
| | - Daniel de Las Heras
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
| | - Matthias Schmidt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
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Reichhardt C, Thibault J, Papanikolaou S, Reichhardt CJO. Laning and clustering transitions in driven binary active matter systems. Phys Rev E 2018; 98:022603. [PMID: 30253470 DOI: 10.1103/physreve.98.022603] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Indexed: 06/08/2023]
Abstract
It is well known that a binary system of nonactive disks that experience driving in opposite directions exhibits jammed, phase separated, disordered, and laning states. In active matter systems, such as a crowd of pedestrians, driving in opposite directions is common and relevant, especially in conditions which are characterized by high pedestrian density and emergency. In such cases, the transition from laning to disordered states may be associated with the onset of a panic state. We simulate a laning system containing active disks that obey run-and-tumble dynamics, and we measure the drift mobility and structure as a function of run length, disk density, and drift force. The activity of each disk can be quantified based on the correlation timescale of the velocity vector. We find that in some cases, increasing the activity can increase the system mobility by breaking up jammed configurations; however, an activity level that is too high can reduce the mobility by increasing the probability of disk-disk collisions. In the laning state, the increase of activity induces a sharp transition to a disordered strongly fluctuating state with reduced mobility. We identify a novel drive-induced clustered laning state that remains stable even at densities below the activity-induced clustering transition of the undriven system. We map out the dynamic phase diagrams highlighting transitions between the different phases as a function of activity, drive, and density.
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Affiliation(s)
- C Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J Thibault
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Department of Mechanical and Aerospace Engineering, Western Virginia University, Morgantown, West Virginia 26506, USA
| | - S Papanikolaou
- Department of Mechanical and Aerospace Engineering, Western Virginia University, Morgantown, West Virginia 26506, USA
- Department of Physics, Western Virginia University, Morgantown, West Virginia 26506, USA
| | - C J O Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Reichhardt C, Reichhardt CJO. Velocity force curves, laning, and jamming for oppositely driven disk systems. SOFT MATTER 2018; 14:490-498. [PMID: 29214253 DOI: 10.1039/c7sm02162c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Using simulations we examine a two-dimensional disk system in which two disk species are driven in opposite directions. We measure the average velocity of one of the species versus the applied driving force and identify four phases as function of drive and disk density: a jammed state, a completely phase separated state, a continuously mixing phase, and a laning phase. The transitions between these phases are correlated with jumps in the velocity-force curves that are similar to the behavior observed at dynamical phase transitions in driven particle systems with quenched disorder such as vortices in type-II superconductors. In some cases the transitions between phases are associated with negative differential mobility in which the average absolute velocity of either species decreases with increasing drive. We also consider the situation where the drive is applied to only one species as well as systems in which both species are driven in the same direction with different drive amplitudes. We show that the phases are robust against the addition of thermal fluctuations. Finally, we discuss how the transitions we observe could be related to absorbing phase transitions where a system in a phase separated or laning regime organizes to a state in which contacts between the disks no longer occur and dynamical fluctuations are lost.
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Affiliation(s)
- C Reichhardt
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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Hao QY, Jiang R, Hu MB, Jia B. Dual phase separation in a two-dimensional driven diffusive system. PHYSICS LETTERS A 2017; 381:1543-1547. [DOI: 10.1016/j.physleta.2017.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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