1
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Máthé MT, Nishikawa H, Araoka F, Jákli A, Salamon P. Electrically activated ferroelectric nematic microrobots. Nat Commun 2024; 15:6928. [PMID: 39164266 PMCID: PMC11336208 DOI: 10.1038/s41467-024-50226-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 07/02/2024] [Indexed: 08/22/2024] Open
Abstract
Ferroelectric nematic liquid crystals are fluids exhibiting spontaneous electric polarization, which is coupled to their long range orientational order. Due to their inherent property of making bound and surface charges, the free surface of ferroelectric nematics becomes unstable in electric fields. Here we show that ferroelectric liquid bridges between two electrode plates undergo distinct interfacial instabilities. In a specific range of frequency and voltage, the ferroelectric fluid bridges move as active interacting particles resembling living organisms like swarming insects, microbes or microrobots. The motion is accompanied by sound emission, as a consequence of piezoelectricity and electrostriction. Statistical analysis of the active particles reveals that the movement can be controlled by the applied voltage, which implies the possible application of the system in new types of microfluidic devices.
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Affiliation(s)
- Marcell Tibor Máthé
- Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, P.O. Box 49, Budapest, Hungary
- Eötvös Loránd University, P.O. Box 32, Budapest, Hungary
| | - Hiroya Nishikawa
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama, Japan
| | - Fumito Araoka
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama, Japan.
| | - Antal Jákli
- Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, P.O. Box 49, Budapest, Hungary.
- Material Science Graduate Program and Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, USA.
- Department of Physics, Kent State University, Kent, OH, USA.
| | - Péter Salamon
- Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, P.O. Box 49, Budapest, Hungary.
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2
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Chen Y, Zhang J. Anomalous flocking in nonpolar granular Brownian vibrators. Nat Commun 2024; 15:6032. [PMID: 39019894 PMCID: PMC11255308 DOI: 10.1038/s41467-024-50479-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 07/09/2024] [Indexed: 07/19/2024] Open
Abstract
Using Brownian vibrators, we investigated the structures and dynamics of quasi-2d granular materials, with packing fractions (ϕ) ranging from 0.111 to 0.832. Our observations revealed a remarkable large-scale flocking behavior in hard granular disk systems, encompassing four distinct phases: granular fluid, flocking fluid, poly-crystal, and crystal. Anomalous flocking emerges at ϕ = 0.317, coinciding with a peak in local density fluctuations, and ceased at ϕ = 0.713 as the system transitioned into a poly-crystal state. The poly-crystal and crystal phases resembled equilibrium hard disks, while the granular and flocking fluids differed significantly from equilibrium systems and previous experiments involving uniformly driven spheres. This disparity suggests that collective motion arises from a competition controlled by volume fraction, involving an active force and an effective attractive interaction resulting from inelastic particle collisions. Remarkably, these findings align with recent theoretical research on the flocking motion of spherical active particles without alignment mechanisms.
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Affiliation(s)
- Yangrui Chen
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Jie Zhang
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
- Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai, China.
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3
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Hecht L, Dong I, Liebchen B. Motility-induced coexistence of a hot liquid and a cold gas. Nat Commun 2024; 15:3206. [PMID: 38615122 PMCID: PMC11016108 DOI: 10.1038/s41467-024-47533-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 04/03/2024] [Indexed: 04/15/2024] Open
Abstract
If two phases exist at the same time, such as a gas and a liquid, they have the same temperature. This fundamental law of equilibrium physics is known to apply even to many non-equilibrium systems. However, recently, there has been much attention in the finding that inertial self-propelled particles like Janus colloids in a plasma or microflyers could self-organize into a hot gas-like phase that coexists with a colder liquid-like phase. Here, we show that a kinetic temperature difference across coexisting phases can occur even in equilibrium systems when adding generic (overdamped) self-propelled particles. In particular, we consider mixtures of overdamped active and inertial passive Brownian particles and show that when they phase separate into a dense and a dilute phase, both phases have different kinetic temperatures. Surprisingly, we find that the dense phase (liquid) cannot only be colder but also hotter than the dilute phase (gas). This effect hinges on correlated motions where active particles collectively push and heat up passive ones primarily within the dense phase. Our results answer the fundamental question if a non-equilibrium gas can be colder than a coexisting liquid and create a route to equip matter with self-organized domains of different kinetic temperatures.
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Affiliation(s)
- Lukas Hecht
- Institute of Condensed Matter Physics, Department of Physics, Technical University of Darmstadt, Darmstadt, Germany
| | - Iris Dong
- Institute of Condensed Matter Physics, Department of Physics, Technical University of Darmstadt, Darmstadt, Germany
| | - Benno Liebchen
- Institute of Condensed Matter Physics, Department of Physics, Technical University of Darmstadt, Darmstadt, Germany.
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4
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Mangeat M, Chakraborty S, Wysocki A, Rieger H. Stationary particle currents in sedimenting active matter wetting a wall. Phys Rev E 2024; 109:014616. [PMID: 38366426 DOI: 10.1103/physreve.109.014616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 01/02/2024] [Indexed: 02/18/2024]
Abstract
Recently it was predicted, on the basis of a lattice gas model, that scalar active matter in a gravitational field would rise against gravity up a confining wall or inside a thin capillary-in spite of repulsive particle-wall interactions [Phys. Rev. Lett. 124, 048001 (2020)0031-900710.1103/PhysRevLett.124.048001]. In this paper we confirm this prediction with sedimenting active Brownian particles (ABPs) in a box numerically and elucidate the mechanism leading to the formation of a meniscus rising above the bulk of the sedimentation region. The height of the meniscus increases with the activity of the system, algebraically with the Péclet number. The formation of the meniscus is determined by a stationary circular particle current, a vortex, centered at the base of the meniscus, whose size and strength increase with the ABP activity. The origin of these vortices can be traced back to the confinement of the ABPs in a box: already the stationary state of ideal (noninteracting) ABPs without gravitation displays circular currents that arrange in a highly symmetric way in the eight octants of the box. Gravitation distorts this vortex configuration downward, leaving two major vortices at the two side walls, with a strong downward flow along the walls. Repulsive interactions between the ABPs change this situation only as soon as motility induced phase separation (MIPS) sets in and forms a dense, sedimented liquid region at the bottom, which pushes the center of the vortex upwards towards the liquid-gas interface. Self-propelled particles therefore represent an impressive realization of scalar active matter that forms stationary particle currents being able to perform visible work against gravity or any other external field, which we predict to be observable experimentally in active colloids under gravitation.
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Affiliation(s)
- Matthieu Mangeat
- Center for Biophysics & Department for Theoretical Physics, Saarland University, D-66123 Saarbrücken, Germany
| | - Shauri Chakraborty
- Center for Biophysics & Department for Theoretical Physics, Saarland University, D-66123 Saarbrücken, Germany
| | - Adam Wysocki
- Center for Biophysics & Department for Theoretical Physics, Saarland University, D-66123 Saarbrücken, Germany
| | - Heiko Rieger
- Center for Biophysics & Department for Theoretical Physics, Saarland University, D-66123 Saarbrücken, Germany
- INM - Leibniz Institute for New Materials, Campus D2 2, D-66123 Saarbrücken, Germany
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5
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Megías A, Santos A. Translational and rotational non-Gaussianities in homogeneous freely evolving granular gases. Phys Rev E 2023; 108:014902. [PMID: 37583179 DOI: 10.1103/physreve.108.014902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 06/13/2023] [Indexed: 08/17/2023]
Abstract
The importance of roughness in the modeling of granular gases has been increasingly considered in recent years. In this paper, a freely evolving homogeneous granular gas of inelastic and rough hard disks or spheres is studied under the assumptions of the Boltzmann kinetic equation. The homogeneous cooling state is studied from a theoretical point of view using a Sonine approximation, in contrast to a previous Maxwellian approach. A general theoretical description is done in terms of d_{t} translational and d_{r} rotational degrees of freedom, which accounts for the cases of spheres (d_{t}=d_{r}=3) and disks (d_{t}=2, d_{r}=1) within a unified framework. The non-Gaussianities of the velocity distribution function of this state are determined by means of the first nontrivial cumulants and by the derivation of non-Maxwellian high-velocity tails. The results are validated by computer simulations using direct simulation Monte Carlo and event-driven molecular dynamics algorithms.
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Affiliation(s)
- Alberto Megías
- Departamento de Física, Universidad de Extremadura, E-06006 Badajoz, Spain
| | - Andrés Santos
- Departamento de Física, Universidad de Extremadura, E-06006 Badajoz, Spain and Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, E-06006 Badajoz, Spain
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6
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Gorce JB, Falcon E. Statistics of a two-dimensional immersed granular gas magnetically forced in volume. Phys Rev E 2023; 107:034903. [PMID: 37073048 DOI: 10.1103/physreve.107.034903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 02/22/2023] [Indexed: 04/20/2023]
Abstract
We present an experimental study of the dynamics of a set of magnets within a fluid in which a remote torque applied by a vertical oscillating magnetic field transfers angular momentum to individual magnets. This system differs from previous experimental studies of granular gas where the energy is injected by vibrating the boundaries. Here, we do not observe any cluster formation, orientational correlation and equipartition of the energy. The magnets' linear velocity distributions are stretched exponentials, similar to three-dimensional boundary-forced dry granular gas systems, but the exponent does not depend on the number of magnets. The value of the exponent of the stretched exponential distributions is close to the value of 3/2 previously derived theoretically. Our results also show that the conversion rate of angular momentum into linear momentum during the collisions controls the dynamics of this homogenously forced granular gas. We report the differences among this homogeneously forced granular gas, ideal gas, and nonequilibrium boundary-forced dissipative granular gas.
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Affiliation(s)
| | - Eric Falcon
- Université Paris Cité, CNRS, MSC, UMR 7057, F-75013 Paris, France
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7
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Han WH, Cheng K, Liu XN, Dong JQ, Chen XS, Huang L. Universal cover-time distributions of random motion in bounded granular gases. CHAOS (WOODBURY, N.Y.) 2023; 33:023127. [PMID: 36859237 DOI: 10.1063/5.0133953] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 01/27/2023] [Indexed: 06/18/2023]
Abstract
The exhaustive random exploration of a complex domain is a fundamental issue in many natural, social, and engineering systems. The key characterizing quantity is the cover time, which is the time to visit every site in the system. One prototypical experimental platform is the confined granular gas, where the random motion of granular particles mimics the wandering of random walkers in a confined region. Here, we investigate the cover-time distribution of the random motion of tracer particles in granular gases confined in four containers to account for different boundary and angle effects and examine whether the cover time of the heterogeneous random motion of the granular gases can be rescaled into the universal Gumbel distribution according to a recent theory [Dong et al., arXiv:2210.05122 (2022)]. It is found that for long cover times, the experimental results are in full accord, while for short cover times, the agreement is reasonable, with noticeable deviations that can be attributed to spatial correlations of the sites in the covering process. Our results, thus, call for further theoretical investigations in order to take into full account these nonideal issues.
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Affiliation(s)
- Wen-Hui Han
- Lanzhou Center for Theoretical Physics and Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou, Gansu 730000, China
| | - Ke Cheng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiao-Nan Liu
- Lanzhou Center for Theoretical Physics and Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou, Gansu 730000, China
| | - Jia-Qi Dong
- Lanzhou Center for Theoretical Physics and Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou, Gansu 730000, China
| | - Xiao-Song Chen
- School of Systems Science, Beijing Normal University, Beijing 100875, China
| | - Liang Huang
- Lanzhou Center for Theoretical Physics and Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou, Gansu 730000, China
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8
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Chen Y, Zhang J. High-energy velocity tails in uniformly heated granular materials. Phys Rev E 2022; 106:L052903. [PMID: 36559423 DOI: 10.1103/physreve.106.l052903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 11/17/2022] [Indexed: 06/17/2023]
Abstract
We experimentally investigate the velocity distributions of quasi-two-dimensional granular materials uniformly heated by an electromagnetic vibrator, where the translational velocity and the rotation of a single particle are Gaussian and independent. We observe the non-Gaussian distributions of particle velocity, with the density-independent high-energy tails characterized by an exponent of β=1.50±0.03 for volume fractions of 0.111≤ϕ≤0.832, covering a wide range of structures and dynamics. Surprisingly, our results are not only in excellent agreement with the prediction of the kinetic theories of granular gas but also hold for an extremely high-volume fraction of ϕ=0.832 where the granular material forms a crystalline solid and the kinetic theory of granular gas fails fantastically. Our experiment suggests that the density-independent high-energy velocity tails of β=1.50 are a characteristic of uniformly heated granular matter.
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Affiliation(s)
- Yangrui Chen
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jie Zhang
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
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9
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Kalz E, Vuijk HD, Abdoli I, Sommer JU, Löwen H, Sharma A. Collisions Enhance Self-Diffusion in Odd-Diffusive Systems. PHYSICAL REVIEW LETTERS 2022; 129:090601. [PMID: 36083684 DOI: 10.1103/physrevlett.129.090601] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 06/15/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
It is generally believed that collisions of particles reduce the self-diffusion coefficient. Here we show that in odd-diffusive systems, which are characterized by diffusion tensors with antisymmetric elements, collisions surprisingly can enhance the self-diffusion. In these systems, due to an inherent curving effect, the motion of particles is facilitated, instead of hindered by collisions leading to a mutual rolling effect. Using a geometric model, we analytically predict the enhancement of the self-diffusion coefficient with increasing density. This counterintuitive behavior is demonstrated in the archetypal odd-diffusive system of Brownian particles under Lorentz force. We validate our findings by many-body Brownian dynamics simulations in dilute systems.
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Affiliation(s)
- Erik Kalz
- Leibniz-Institut für Polymerforschung Dresden, Institut Theorie der Polymere, 01069 Dresden, Deutschland
- Technische Universität Dresden, Institut für Theoretische Physik, 01069 Dresden, Deutschland
| | - Hidde Derk Vuijk
- Leibniz-Institut für Polymerforschung Dresden, Institut Theorie der Polymere, 01069 Dresden, Deutschland
| | - Iman Abdoli
- Leibniz-Institut für Polymerforschung Dresden, Institut Theorie der Polymere, 01069 Dresden, Deutschland
| | - Jens-Uwe Sommer
- Leibniz-Institut für Polymerforschung Dresden, Institut Theorie der Polymere, 01069 Dresden, Deutschland
- Technische Universität Dresden, Institut für Theoretische Physik, 01069 Dresden, Deutschland
| | - Hartmut Löwen
- Heinrich Heine-Universität Düsseldorf, Institut für Theoretische Physik II: Weiche Materie, 40225 Düsseldorf, Deutschland
| | - Abhinav Sharma
- Leibniz-Institut für Polymerforschung Dresden, Institut Theorie der Polymere, 01069 Dresden, Deutschland
- Technische Universität Dresden, Institut für Theoretische Physik, 01069 Dresden, Deutschland
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10
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Cheng K, Liu P, Yang M, Hou M. Experimental investigation of active noise on a rotor in an active granular bath. SOFT MATTER 2022; 18:2541-2548. [PMID: 35166750 DOI: 10.1039/d1sm01798e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In an active bath, besides thermal noise, immersed passive objects also persistently experience collisions from active particles, which are often coarse-grained into a colored active noise with an assumed exponential time correlation. The exponentially correlated active noise extremely simplifies the theoretical description of immersed passive objects but so far lacks direct experimental verification. Here, we experimentally investigate the active noise subjected by a passive rotor confined in an active granular bath. On the basis of Langevin dynamics, we extract the characteristic of the active noise by analyzing the power spectrum of the rotor trajectory. Our experimental results find that the active noise experienced by the granular rotor does show an exponential time correlation to a good extent, even though due to the small experimental system and low collision frequency, the profile of the active noise in our system is non-Gaussian. Our findings give direct experimental evidence, which supports the widely-used active Ornstein-Uhlenbeck particle model in our dry active system.
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Affiliation(s)
- Ke Cheng
- Beijing National Laboratory for Condensed Matter Physics and Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
| | - Peng Liu
- Beijing National Laboratory for Condensed Matter Physics and Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325001, China
| | - Mingcheng Yang
- Beijing National Laboratory for Condensed Matter Physics and Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Meiying Hou
- Beijing National Laboratory for Condensed Matter Physics and Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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11
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Exploring the Origin of Maximum Entropy States Relevant to Resonant Modes in Modern Chladni Plates. ENTROPY 2022; 24:e24020215. [PMID: 35205510 PMCID: PMC8870825 DOI: 10.3390/e24020215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 12/10/2022]
Abstract
Abstract: The resonant modes generated from the modern Chladni experiment are systematically confirmed to intimately correspond to the maximum entropy states obtained from the inhomogeneous Helmholtz equation for the square and equilateral triangle plates [...]
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12
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Numerical simulation of particle velocity and coordination number under the slumping regime in a rotating drum. POWDER TECHNOL 2021. [DOI: 10.1016/j.powtec.2021.09.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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13
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Megías A, Santos A. Hydrodynamics of granular gases of inelastic and rough hard disks or spheres. I. Transport coefficients. Phys Rev E 2021; 104:034901. [PMID: 34654090 DOI: 10.1103/physreve.104.034901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/17/2021] [Indexed: 11/07/2022]
Abstract
The transport coefficients for dilute granular gases of inelastic and rough hard disks or spheres with constant coefficients of normal (α) and tangential (β) restitution are obtained in a unified framework as functions of the number of translational (d_{t}) and rotational (d_{r}) degrees of freedom. The derivation is carried out by means of the Chapman-Enskog method with a Sonine-like approximation in which, in contrast to previous approaches, the reference distribution function for angular velocities does not need to be specified. The well-known case of purely smooth d-dimensional particles is recovered by setting d_{t}=d and formally taking the limit d_{r}→0. In addition, previous results [G. M. Kremer, A. Santos, and V. Garzó, Phys. Rev. E 90, 022205 (2014)10.1103/PhysRevE.90.022205] for hard spheres are reobtained by taking d_{t}=d_{r}=3, while novel results for hard-disk gases are derived with the choice d_{t}=2, d_{r}=1. The singular quasismooth limit (β→-1) and the conservative Pidduck's gas (α=β=1) are also obtained and discussed.
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Affiliation(s)
- Alberto Megías
- Departamento de Física, Universidad de Extremadura, E-06006 Badajoz, Spain
| | - Andrés Santos
- Departamento de Física, Universidad de Extremadura, E-06006 Badajoz, Spain.,Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, E-06006 Badajoz, Spain
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14
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Abstract
Granular particles exhibit rich collective behaviors on vibration beds, but the motion of an isolated particle is not well understood even for uniform particles with a simple shape such as disks or spheres. Here we measured the motion of a single disk confined to a quasi-two-dimensional horizontal box on a vertically vibrating stage. The translational displacements obey compressed exponential distributions whose exponent [Formula: see text] increases with the frequency, while the rotational displacements exhibit unimodal distributions at low frequencies and bimodal distributions at high frequencies. During short time intervals, the translational displacements are subdiffusive and negatively correlated, while the rotational displacements are superdiffusive and positively correlated. After prolonged periods, the rotational displacements become diffusive and their correlations decay to zero. Both the rotational and the translational displacements exhibit white noise at low frequencies, and blue noise for translational motions and Brownian noise for rotational motions at high frequencies. The translational kinetic energy obeys Boltzmann distribution while the rotational kinetic energy deviates from it. Most energy is distributed in translational motions at low frequencies and in rotational motions at high frequencies, which violates the equipartition theorem. Translational and rotational motions are not correlated. These experimental results show that the random diffusion of such driven particles is distinct from thermal motion in both the translational and rotational degrees of freedom, which poses new challenges to theory. The results cast new light on the motion of individual particles and the collective motion of driven granular particles.
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15
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López-Castaño MA, González-Saavedra JF, Rodríguez-Rivas A, Abad E, Yuste SB, Vega Reyes F. Pseudo-two-dimensional dynamics in a system of macroscopic rolling spheres. Phys Rev E 2021; 103:042903. [PMID: 34005988 DOI: 10.1103/physreve.103.042903] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 03/18/2021] [Indexed: 11/07/2022]
Abstract
We study in this work the dynamics of a collection of identical hollow spheres (ping-pong balls) that rest on a horizontal metallic grid. Fluidization is achieved by means of a turbulent air current coming from below. The upflow is adjusted so that the particles do not levitate over the grid, resulting in quasi-two-dimensional dynamics. We show that the behavior of diffusion and correlations in this system is particularly rich. Noticeably as well (and related to the complex dynamical behavior), a variety of phases appear, with important peculiarities with respect to analogous setups. We observe gas, liquid, glass, and hexagonal crystal phases. Most notably, we show that the melting of the hexagonal crystal occurs in coexistence with a liquid phase. This strikingly differs from the corresponding transition in a purely two-dimensional systems of air-fluidized disks, for which no phase coexistence has been reported in the literature.
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Affiliation(s)
- M A López-Castaño
- Departamento de Física, Universidad de Extremadura, Avenida Elvas s/n, 06071 Badajoz, Spain
| | - J F González-Saavedra
- Departamento de Física, Universidad de Extremadura, Avenida Elvas s/n, 06071 Badajoz, Spain
| | - A Rodríguez-Rivas
- Departamento de Matemática Aplicada II, Escuela Politécnica Superior, Universidad de Sevilla, Virgen de Africa, 7, 41011 Sevilla, Spain
| | - E Abad
- Departamento de Física Aplicada, Centro Universitario de Mérida, Universidad de Extremadura, 06800 Mérida, Spain.,Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, Avenida Elvas s/n, 06071 Badajoz, Spain
| | - S B Yuste
- Departamento de Física, Universidad de Extremadura, Avenida Elvas s/n, 06071 Badajoz, Spain.,Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, Avenida Elvas s/n, 06071 Badajoz, Spain
| | - F Vega Reyes
- Departamento de Física, Universidad de Extremadura, Avenida Elvas s/n, 06071 Badajoz, Spain.,Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, Avenida Elvas s/n, 06071 Badajoz, Spain
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16
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Scholz C, Ldov A, Pöschel T, Engel M, Löwen H. Surfactants and rotelles in active chiral fluids. SCIENCE ADVANCES 2021; 7:eabf8998. [PMID: 33853787 PMCID: PMC8046367 DOI: 10.1126/sciadv.abf8998] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/25/2021] [Indexed: 05/03/2023]
Abstract
Surfactant molecules migrate to interfaces, reduce interfacial tension, and form micelles. All of these behaviors occur at or near equilibrium. Here, we describe active analogs of surfactants that operate far from equilibrium in active chiral fluids. Unlike molecular surfactants, the amphiphilic character of surfactants in active chiral fluids is a consequence of their activity. Our fluid of choice is a mixture of spinners that demixes into left-handed and right-handed chiral fluid domains. We realize spinners in experiment with three-dimensionally printed vibrots. Vibrot surfactants are chains of vibrots containing both types of handedness. Experiments demonstrate the affinity of double-stranded chains to interfaces, where they glide along and act as mixing agents. Simulations access larger systems in which single-stranded chains form spinning vesicles, termed rotelles. Rotelles are the chiral analogs of micelles. Rotelle formation is a ratchet mechanism catalyzed by the vorticity of the chiral fluid and only exist far from equilibrium.
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Affiliation(s)
- Christian Scholz
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.
| | - Anton Ldov
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Thorsten Pöschel
- Institute for Multiscale Simulation Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Michael Engel
- Institute for Multiscale Simulation Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
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17
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Noirhomme M, Cazaubiel A, Falcon E, Fischer D, Garrabos Y, Lecoutre-Chabot C, Mawet S, Opsomer E, Palencia F, Pillitteri S, Vandewalle N. Particle Dynamics at the Onset of the Granular Gas-Liquid Transition. PHYSICAL REVIEW LETTERS 2021; 126:128002. [PMID: 33834798 DOI: 10.1103/physrevlett.126.128002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 03/04/2021] [Indexed: 06/12/2023]
Abstract
We study experimentally the dynamical behavior of few large tracer particles placed in a quasi-2D granular "gas" made of many small beads in a low-gravity environment. Multiple inelastic collisions transfer momentum from the uniaxially driven gas to the tracers whose velocity distributions are studied through particle tracking. Analyzing these distributions for an increasing system density reveals that translational energy equipartition is reached at the onset of the gas-liquid granular transition corresponding to the emergence of local clusters. The dynamics of a few tracer particles thus appears as a simple and accurate tool to detect this transition. A model is proposed for describing accurately the formation of local heterogeneities.
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Affiliation(s)
- M Noirhomme
- GRASP, CESAM Research Unit, Institut de Physique B5a, Sart Tilman, University of Liège, B-4000 Liège, Belgium
| | - A Cazaubiel
- Université de Paris, Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75013 Paris, France
| | - E Falcon
- Université de Paris, Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75013 Paris, France
| | - D Fischer
- Institute of Physics, Otto von Guericke University, D-39106 Magdeburg, Germany
| | - Y Garrabos
- CNRS, Université de Bordeaux, Bordeaux INP, ICMCB, UMR 5026, F-33600 Pessac, France
| | - C Lecoutre-Chabot
- CNRS, Université de Bordeaux, Bordeaux INP, ICMCB, UMR 5026, F-33600 Pessac, France
| | - S Mawet
- GRASP, CESAM Research Unit, Institut de Physique B5a, Sart Tilman, University of Liège, B-4000 Liège, Belgium
| | - E Opsomer
- GRASP, CESAM Research Unit, Institut de Physique B5a, Sart Tilman, University of Liège, B-4000 Liège, Belgium
| | - F Palencia
- CNRS, Université de Bordeaux, Bordeaux INP, ICMCB, UMR 5026, F-33600 Pessac, France
| | - S Pillitteri
- GRASP, CESAM Research Unit, Institut de Physique B5a, Sart Tilman, University of Liège, B-4000 Liège, Belgium
| | - N Vandewalle
- GRASP, CESAM Research Unit, Institut de Physique B5a, Sart Tilman, University of Liège, B-4000 Liège, Belgium
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18
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Brilliantov NV, Abutuqayqah H, Tyukin IY, Matveev SA. Swirlonic state of active matter. Sci Rep 2020; 10:16783. [PMID: 33033334 PMCID: PMC7546729 DOI: 10.1038/s41598-020-73824-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/15/2020] [Indexed: 11/13/2022] Open
Abstract
We report a novel state of active matter-a swirlonic state. It is comprised of swirlons, formed by groups of active particles orbiting their common center of mass. These quasi-particles demonstrate a surprising behavior: In response to an external load they move with a constant velocity proportional to the applied force, just as objects in viscous media. The swirlons attract each other and coalesce forming a larger, joint swirlon. The coalescence is extremely slow, decelerating process, resulting in a rarified state of immobile quasi-particles. In addition to the swirlonic state, we observe gaseous, liquid and solid states, depending on the inter-particle and self-driving forces. Interestingly, in contrast to molecular systems, liquid and gaseous states of active matter do not coexist. We explain this unusual phenomenon by the lack of fast particles in active matter. We perform extensive numerical simulations and theoretical analysis. The predictions of the theory agree qualitatively and quantitatively with the simulation results.
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Affiliation(s)
- Nikolai V Brilliantov
- Skolkovo Institute of Science and Technology, Moscow, Russia
- Department of Mathematics, University of Leicester, Leicester, LE1 7RH, UK
| | - Hajar Abutuqayqah
- Department of Mathematics, University of Leicester, Leicester, LE1 7RH, UK
| | - Ivan Yu Tyukin
- Department of Mathematics, University of Leicester, Leicester, LE1 7RH, UK
- Saint Petersburg Electrotechnical University "LETI", Professora Popova 5, St. Petersburg, Russia
| | - Sergey A Matveev
- Skolkovo Institute of Science and Technology, Moscow, Russia.
- Marchuk Institute of Numerical Mathematics, RAS, Gubkin st. 8, Moscow, Russia.
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19
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Yu P, Schröter M, Sperl M. Velocity Distribution of a Homogeneously Cooling Granular Gas. PHYSICAL REVIEW LETTERS 2020; 124:208007. [PMID: 32501095 DOI: 10.1103/physrevlett.124.208007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 11/27/2019] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
In contrast to molecular gases, granular gases are characterized by inelastic collisions and require therefore permanent driving to maintain a constant kinetic energy. The kinetic theory of granular gases describes how the average velocity of the particles decreases after the driving is shut off. Moreover, it predicts that the rescaled particle velocity distribution will approach a stationary state with overpopulated high-velocity tails as compared to the Maxwell-Boltzmann distribution. While this fundamental theoretical result was reproduced by numerical simulations, an experimental confirmation is still missing. Using a microgravity experiment that allows the spatially homogeneous excitation of spheres via magnetic fields, we confirm the theoretically predicted exponential decay of the tails of the velocity distribution.
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Affiliation(s)
- Peidong Yu
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Cologne, Germany
- Institut für Theoretische Physik, Universität zu Köln, 50937 Cologne, Germany
| | - Matthias Schröter
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Cologne, Germany
| | - Matthias Sperl
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Cologne, Germany
- Institut für Theoretische Physik, Universität zu Köln, 50937 Cologne, Germany
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20
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Abstract
Due to its inherent out-of-equilibrium nature, active matter in confinement may exhibit collective behavior absent in unconfined systems. Extensive studies have indicated that hydrodynamic or steric interactions between active particles and boundary play an important role in the emergence of collective behavior. However, besides introducing external couplings at the single-particle level, the confinement also induces an inhomogeneous density distribution due to particle-position correlations, whose effect on collective behavior remains unclear. Here, we investigate this effect in a minimal chiral active matter composed of self-spinning rotors through simulation, experiment, and theory. We find that the density inhomogeneity leads to a position-dependent frictional stress that results from interrotor friction and couples the spin to the translation of the particles, which can then drive a striking spatially oscillating collective motion of the chiral active matter along the confinement boundary. Moreover, depending on the oscillation properties, the collective behavior has three different modes as the packing fraction varies. The structural origins of the transitions between the different modes are well identified by the percolation of solid-like regions or the occurrence of defect-induced particle rearrangement. Our results thus show that the confinement-induced inhomogeneity, dynamic structure, and compressibility have significant influences on collective behavior of active matter and should be properly taken into account.
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21
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Castillo G, Merminod S, Falcon E, Berhanu M. Tuning the distance to equipartition by controlling the collision rate in a driven granular gas experiment. Phys Rev E 2020; 101:032903. [PMID: 32289943 DOI: 10.1103/physreve.101.032903] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 02/11/2020] [Indexed: 11/07/2022]
Abstract
In a granular gas experiment of magnetized particles confined in a thin layer, the rate of dissipative collisions is tuned by adjusting the amplitude of an external magnetic field. The velocity statistics are analyzed using the dynamic and static structure factors of transverse velocity modes. Using the fluctuating hydrodynamics theory, we measure the deviation from kinetic energy equipartition in this out-of-equilibrium system as a function of the dissipative collision rate. When the collision rate is decreased, the distance to equipartition becomes smaller, meaning that the dynamical properties of this granular gas approach by analogy those of a molecular gas in thermal equilibrium.
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Affiliation(s)
- Gustavo Castillo
- Instituto de Ciencias de la Ingienería, Universidad O'Higgins, 2841959 Rancagua, Chile
| | - Simon Merminod
- MSC, Université de Paris, Université Paris Diderot, CNRS (UMR 7057), 75013 Paris, France
| | - Eric Falcon
- MSC, Université de Paris, Université Paris Diderot, CNRS (UMR 7057), 75013 Paris, France
| | - Michael Berhanu
- MSC, Université de Paris, Université Paris Diderot, CNRS (UMR 7057), 75013 Paris, France
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22
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Mandal S, Liebchen B, Löwen H. Motility-Induced Temperature Difference in Coexisting Phases. PHYSICAL REVIEW LETTERS 2019; 123:228001. [PMID: 31868412 DOI: 10.1103/physrevlett.123.228001] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Indexed: 06/10/2023]
Abstract
Unlike in thermodynamic equilibrium where coexisting phases always have the same temperature, here we show that systems comprising "active" self-propelled particles can self-organize into two coexisting phases at different kinetic temperatures, which are separated from each other by a sharp and persistent temperature gradient. Contrasting previous studies that have focused on overdamped descriptions of active particles, we show that a "hot-cold coexistence" occurs if and only if accounting for inertia, which is significant, e.g., in activated dusty plasmas, microflyers, whirling fruits, or beetles at interfaces. Our results exemplify a route to use active particles to create a self-sustained temperature gradient across coexisting phases. This phenomenon is fundamentally beyond equilibrium physics and is accompanied by a slow coarsening law with an exponent significantly smaller than the universal 1/3 exponent seen in both equilibrium systems and overdamped active Brownian particles.
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Affiliation(s)
- Suvendu Mandal
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - Benno Liebchen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
- Theorie Weicher Materie, Fachbereich Physik, Technische Universität Darmstadt, Hochschulstraße 12, 64289 Darmstadt, Germany
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
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23
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Chen Y, Wang W. Reticulate collisional structure in boundary-driven granular gases. Phys Rev E 2019; 100:042908. [PMID: 31770908 DOI: 10.1103/physreve.100.042908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Indexed: 11/07/2022]
Abstract
We report a peculiar head-on collision network between two vibrating boundaries in experiments performed during a parabolic flight and in a laboratory using horizontal vibration. This structure is a new ordering, which is due to an orientation correlation between the relative position and velocity of any particle pair. It weakens the collision frequency and produces a long-range boundary effect. Moreover, we find the molecular chaos assumption is violated in a larger portion of the phase space. Using an anisotropic distribution model, we modify angular integration results and compare them to the results of the kinetic theory.
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Affiliation(s)
- Yanpei Chen
- State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Wei Wang
- State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China and University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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24
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Rana S, Samsuzzaman M, Saha A. Tuning the self-organization of confined active particles by the steepness of the trap. SOFT MATTER 2019; 15:8865-8878. [PMID: 31616877 DOI: 10.1039/c9sm01691k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We consider the collective dynamics of self-propelling particles in two dimensions. They can align themselves according to the direction of propulsion of their neighbours, together with small rotational fluctuations. They also interact with each other via soft, isotropic, repulsive potentials. The particles are confined in a circular trap. The steepness of the trap is tuneable. The average packing fraction of the particles is low. When the trap is steep, particles flock along its boundary. They form a polar cluster that spreads over the boundary. The cluster is not spatially ordered. We show that when the steepness is decreased beyond a threshold value, the cluster becomes round and compact and eventually spatial order (hexagonal) emerges in addition to the pre-established polar order. We investigate the kinetics of such ordering. We find that while rotating around the centre of the trap along its circular boundary, the cluster needs to roll around its centre of mass to be spatially ordered. We have studied the stability of the order when the trap is suddenly switched off. We find that for the particles with velocity alignment interaction, the decay of the spatial order is much slower than the particles without the alignment interaction.
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Affiliation(s)
- Shubhashis Rana
- S. N. Bose National Centre For Basic Sciences, Kolkata, 700098, India.
| | - Md Samsuzzaman
- Department of Physics, Savitribai Phule Pune University, Pune, 411007, India.
| | - Arnab Saha
- Department of Physics, Savitribai Phule Pune University, Pune, 411007, India.
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25
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Ji S, Wang S, Peng Z. Influence of external pressure on granular flow in a cylindrical silo based on discrete element method. POWDER TECHNOL 2019. [DOI: 10.1016/j.powtec.2019.08.083] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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26
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Tao X, Tu X, Wu H. A new development in magnetic particle tracking technology and its application in a sheared dense granular flow. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:065116. [PMID: 31255032 DOI: 10.1063/1.5100739] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 06/01/2019] [Indexed: 06/09/2023]
Abstract
This paper presents a new development in the magnetic particle tracking (MPT) technology that measures the translational and rotational motions of a small particle. A main advantage of MPT is that it is able to track objects in an opaque environment without using radioactive material or X-rays. In addition, it can provide information about the orientation and rotation of the object, which is difficult to obtain using other technologies. However, the reconstruction process of MPT using standard optimization approaches is very time consuming and, therefore, limits its applications. In this work, two new MPT reconstruction algorithms are examined and the results are compared with the optimization approach. The extended Kalman filter (EKF) algorithm has the same accuracy as the optimization method but is orders of magnitude faster. The speed of the sequential importance sampling approach is between those of the above two methods. The accuracy of position obtained using EKF is about 0.6%, and the uncertainty of orientation is less than 1.5°. The MPT is applied to measure a dense granular shear flow to investigate the spatial distribution of a tracer particle.
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Affiliation(s)
- Xingtian Tao
- Aerospace Engineering Department, University of Kansas, Lawrence, Kansas 66045, USA
| | - Xuemin Tu
- Department of Mathematics, University of Kansas, Lawrence, Kansas 66045, USA
| | - Huixuan Wu
- Aerospace Engineering Department, University of Kansas, Lawrence, Kansas 66045, USA
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27
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Lei QL, Ciamarra MP, Ni R. Nonequilibrium strongly hyperuniform fluids of circle active particles with large local density fluctuations. SCIENCE ADVANCES 2019; 5:eaau7423. [PMID: 30746459 PMCID: PMC6357732 DOI: 10.1126/sciadv.aau7423] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 12/12/2018] [Indexed: 06/09/2023]
Abstract
Disordered hyperuniform structures are an exotic state of matter having vanishing long-wavelength density fluctuations similar to perfect crystals but without long-range order. Although its importance in materials science has been brought to the fore in past decades, the rational design of experimentally realizable disordered strongly hyperuniform microstructures remains challenging. Here we find a new type of nonequilibrium fluid with strong hyperuniformity in two-dimensional systems of chiral active particles, where particles perform independent circular motions of the radius R with the same handedness. This new hyperuniform fluid features a special length scale, i.e., the diameter of the circular trajectory of particles, below which large density fluctuations are observed. By developing a dynamic mean-field theory, we show that the large local density fluctuations can be explained as a motility-induced microphase separation, while the Fickian diffusion at large length scales and local center-of-mass-conserved noises are responsible for the global hyperuniformity.
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Affiliation(s)
- Qun-Li Lei
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
| | - Massimo Pica Ciamarra
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- CNR-SPIN, Dipartimento di Scienze Fisiche, Università di Napoli Federico II, I-80126 Napoli, Italy
| | - Ran Ni
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
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28
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Liu P, Hrenya CM. Cluster-Induced Deagglomeration in Dilute Gravity-Driven Gas-Solid Flows of Cohesive Grains. PHYSICAL REVIEW LETTERS 2018; 121:238001. [PMID: 30576183 DOI: 10.1103/physrevlett.121.238001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 09/16/2018] [Indexed: 06/09/2023]
Abstract
Clustering is often presumed to lead to enhanced agglomeration between cohesive grains due to the reduced relative velocities of particles within a cluster. Our discrete-particle simulations on gravity-driven, gas-solid flows of cohesive grains exhibit the opposite trend, revealing a new mechanism we coin "cluster-induced deagglomeration." Specifically, we examine relatively dilute gas-solid flows and isolate agglomerates of cohesive origin from overall heterogeneities in the system, i.e., agglomerates of cohesive origin and clusters of hydrodynamic origin. We observe enhanced clustering with an increasing system size (as is the norm for noncohesive systems) as well as reduced agglomeration. The reduced agglomeration is traced to the increased collisional impact velocities of particles at the surface of a cluster; i.e., higher levels of clustering lead to larger relative velocities between the clustered and nonclustered regions, thereby serving as an additional source of granular temperature. This physical picture is further evidenced by a theoretical model based on a balance between the generation and breakage rates of agglomerates. Finally, cluster-induced deagglomeration also provides an explanation for a surprising saturation of agglomeration levels in gravity-driven, gas-solid systems with increasing levels of cohesion, as opposed to the monotonically increasing behavior seen in free-evolving or driven granular systems in the absence of gravity. Namely, higher cohesion leads to more energy dissipation, which is associated with competing effects: enhanced agglomeration and enhanced clustering, the latter of which results in more cluster-induced deagglomeration.
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Affiliation(s)
- Peiyuan Liu
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA
| | - Christine M Hrenya
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA
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29
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Scholz C, Jahanshahi S, Ldov A, Löwen H. Inertial delay of self-propelled particles. Nat Commun 2018; 9:5156. [PMID: 30514839 PMCID: PMC6279816 DOI: 10.1038/s41467-018-07596-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/12/2018] [Indexed: 12/29/2022] Open
Abstract
The motion of self-propelled massive particles through a gaseous medium is dominated by inertial effects. Examples include vibrated granulates, activated complex plasmas and flying insects. However, inertia is usually neglected in standard models. Here, we experimentally demonstrate the significance of inertia on macroscopic self-propelled particles. We observe a distinct inertial delay between orientation and velocity of particles, originating from the finite relaxation times in the system. This effect is fully explained by an underdamped generalisation of the Langevin model of active Brownian motion. In stark contrast to passive systems, the inertial delay profoundly influences the long-time dynamics and enables new fundamental strategies for controlling self-propulsion in active matter.
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Affiliation(s)
- Christian Scholz
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
| | - Soudeh Jahanshahi
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Anton Ldov
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
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30
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Kopera BAF, Retsch M. Computing the 3D Radial Distribution Function from Particle Positions: An Advanced Analytic Approach. Anal Chem 2018; 90:13909-13914. [PMID: 30403841 DOI: 10.1021/acs.analchem.8b03157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The radial distribution function, g( r), is ubiquitously used to analyze the internal structure of particulate systems. However, experimentally derived particle coordinates are always confined to a finite sample volume. This poses a particular challenge on computing g( r): Once the radial distance, r, extends beyond the sample boundaries in at least one dimension, substantial deviations from the true g( r) function can occur. State of the art algorithms for g( r) mitigate this issue for instance by using artificial periodic boundary conditions. However, ignoring the finite nature of the sample volume distorts g( r) significantly. Here, we present a simple, analytic algorithm for the computation of g( r) in finite samples. No additional assumptions about the sample are required. The key idea is to use an analytic solution for the intersection volume between a spherical shell and the sample volume. In addition, we discovered a natural upper bound for the radial distance that only depends on sample size and shape. This analytic approach will prove to be invaluable for the quantitative analysis of the increasing amount of experimentally derived tomography data.
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Affiliation(s)
- Bernd A F Kopera
- Department of Chemistry , University of Bayreuth , Universitätsstraße 30 , 95447 Bayreuth , Germany
| | - Markus Retsch
- Department of Chemistry , University of Bayreuth , Universitätsstraße 30 , 95447 Bayreuth , Germany
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31
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Point-driven modern Chladni figures with symmetry breaking. Sci Rep 2018; 8:10844. [PMID: 30022128 PMCID: PMC6052176 DOI: 10.1038/s41598-018-29244-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 07/05/2018] [Indexed: 01/13/2023] Open
Abstract
Point-driven modern Chladni figures subject to the symmetry breaking are systematically unveiled by developing a theoretical model and making experimental confirmation in the orthotropic brass. The plates with square shape are employed in the exploration based on the property that the orientation-dependent elastic anisotropy can be controlled by cutting the sides with a rotation angle with respect to the characteristic axes of the brass. Experimental results reveal that the orientation symmetry breaking not only causes the redistribution of resonant frequencies but also induces more resonant modes. More intriguingly, the driving position in some of new resonant modes can turn into the nodal point, whereas this position is always the anti-node in the isotropic case. The theoretical model is analytically developed by including a dimensionless parameter to consider the orientation symmetry-breaking effect in a generalized way. It is numerically verified that all experimental resonant frequencies and Chladni patterns can be well reconstructed with the developed model. The good agreement between theoretical calculations and experimental observations confirms the feasibility of using the developed model to analyze the modern Chladni experiment with orientation symmetry breaking. The developed model is believed to offer a powerful tool to build important database of plate resonant modes for the applications of controlling collective motions of micro objects.
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32
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Workamp M, Ramirez G, Daniels KE, Dijksman JA. Symmetry-reversals in chiral active matter. SOFT MATTER 2018; 14:5572-5580. [PMID: 29873387 DOI: 10.1039/c8sm00402a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We perform experiments on an active granular material composed of individually-driven, spinning disks confined within a circular arena. Small bumps at the outer edges of the disks provide a variable amount of interparticle coupling in the form of geometric friction. The disks each spin counter-clockwise, but undergo a transition in their collective circulation around the center of the arena, from a clockwise orbit to a counter-clockwise orbit, as a function of packing fraction φ. We identify that, unlike for vibrated granular gases, the particles' velocity distributions are Gaussian over a large range of φ. By fitting the speed distribution to a Maxwell-Boltzmann distribution, we identify a temperature-like parameter which is a universal function of φ; this parameter is also equal to the mean translational energy of the particles. We quantify the collective circulation via its solid-body-like rotation rate, and find that this is a universal function centered around a critical packing fraction. In addition, the ratio of orbital kinetic energy to spin kinetic energy is also a universal function for non-zero geometric friction. These findings highlight the important role of both the type of driving and the interparticle interactions (here, geometric friction) in controlling the collective behavior of active granular systems.
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Affiliation(s)
- Marcel Workamp
- Physical Chemistry and Soft Matter, Wageningen University & Research, Wageningen, The Netherlands.
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33
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Farhadi S, Machaca S, Aird J, Torres Maldonado BO, Davis S, Arratia PE, Durian DJ. Dynamics and thermodynamics of air-driven active spinners. SOFT MATTER 2018; 14:5588-5594. [PMID: 29882572 DOI: 10.1039/c8sm00403j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report on the collective behavior of active particles in which energy is continuously supplied to rotational degrees of freedom. The active spinners are 3D-printed disks, 1 cm in diameter, that have an embedded fan-like structure, such that a sub-levitating up-flow of air forces them to spin. Single spinners exhibit Brownian motion with a narrow Gaussian velocity distribution function, P(v), for translational motion. We study the evolution of P(v) as the packing fraction and the average single particle spin speeds are varied. The interparticle hydrodynamic interaction is negligible, and the dynamics is dominated by hyperelastic collisions and dissipative forces. As expected for nonequilibrium systems, P(v) for a collection of many spinners deviates from Gaussian behavior. However, unlike translationally active systems, phase separation is not observed, and the system remains spatially homogeneous. We then search for a near-equilibrium counterpart for our active spinners by measuring the equation of state. Interestingly, it agrees well with a hard-sphere model, despite the dissipative nature of the single particle dynamics.
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Santos A. Interplay between polydispersity, inelasticity, and roughness in the freely cooling regime of hard-disk granular gases. Phys Rev E 2018; 98:012904. [PMID: 30110735 DOI: 10.1103/physreve.98.012904] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Indexed: 11/07/2022]
Abstract
A polydisperse granular gas made of inelastic and rough hard disks is considered. Focus is laid on the kinetic-theory derivation of the partial energy production rates and the total cooling rate as functions of the partial densities and temperatures (both translational and rotational) and of the parameters of the mixture (masses, diameters, moments of inertia, and mutual coefficients of normal and tangential restitution). The results are applied to the homogeneous cooling state of the system and the associated nonequipartition of energy among the different components and degrees of freedom. It is found that disks typically present a stronger rotational-translational nonequipartition but a weaker component-component nonequipartition than spheres. A noteworthy "mimicry" effect is unveiled, according to which a polydisperse gas of disks having common values of the coefficient of restitution and of the reduced moment of inertia can be made indistinguishable from a monodisperse gas in what concerns the degree of rotational-translational energy nonequipartition. This effect requires the mass of a disk of component i to be approximately proportional to 2σ_{i}+〈σ〉, where σ_{i} is the diameter of the disk and 〈σ〉 is the mean diameter.
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Affiliation(s)
- Andrés Santos
- Departamento de Física and Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, E-06071 Badajoz, Spain
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Aumaître S, Behringer RP, Cazaubiel A, Clément E, Crassous J, Durian DJ, Falcon E, Fauve S, Fischer D, Garcimartín A, Garrabos Y, Hou M, Jia X, Lecoutre C, Luding S, Maza D, Noirhomme M, Opsomer E, Palencia F, Pöschel T, Schockmel J, Sperl M, Stannarius R, Vandewalle N, Yu P. An instrument for studying granular media in low-gravity environment. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:075103. [PMID: 30068123 DOI: 10.1063/1.5034061] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A new experimental facility has been designed and constructed to study driven granular media in a low-gravity environment. This versatile instrument, fully automatized, with a modular design based on several interchangeable experimental cells, allows us to investigate research topics ranging from dilute to dense regimes of granular media such as granular gas, segregation, convection, sound propagation, jamming, and rheology-all without the disturbance by gravitational stresses active on Earth. Here, we present the main parameters, protocols, and performance characteristics of the instrument. The current scientific objectives are then briefly described and, as a proof of concept, some first selected results obtained in low gravity during parabolic flight campaigns are presented.
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Affiliation(s)
- S Aumaître
- SPEC, DSM, CEA-Saclay, CNRS URA 2464, F-91191 Gif-sur-Yvette, France
| | - R P Behringer
- Department of Physics, Duke University, Durham, North Carolina 27708-0305, USA
| | - A Cazaubiel
- Université Paris Diderot, SPC, MSC, UMR 7057 CNRS, F-75013 Paris, France
| | - E Clément
- PMMH, ESPCI, UMR 7636 CNRS, F-75005 Paris, France
| | - J Crassous
- Université Rennes 1, IPR, UMR 6251 CNRS, F-35042 Rennes, France
| | - D J Durian
- University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396, USA
| | - E Falcon
- Université Paris Diderot, SPC, MSC, UMR 7057 CNRS, F-75013 Paris, France
| | - S Fauve
- École Normale Supérieure, LPS, CNRS, UMR 8550, F-75005 Paris, France
| | - D Fischer
- IEP, Otto von Guericke Universität, D-39106 Magdeburg, Germany
| | - A Garcimartín
- DFMA, Universidad de Navarra, E-31080 Pamplona, Spain
| | - Y Garrabos
- CNRS, ICMCB, Université de Bordeaux, UMR 5026, F-33600 Pessac, France
| | - M Hou
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - X Jia
- Institut Langevin, ESPCI Paris, PSL, CNRS, F-75005 Paris, France
| | - C Lecoutre
- CNRS, ICMCB, Université de Bordeaux, UMR 5026, F-33600 Pessac, France
| | - S Luding
- MSM, University of Twente, 7500 AE Enschede, The Netherlands
| | - D Maza
- DFMA, Universidad de Navarra, E-31080 Pamplona, Spain
| | - M Noirhomme
- GRASP, Institute of Physics B5a, University of Liège, B-4000 Liège, Belgium
| | - E Opsomer
- GRASP, Institute of Physics B5a, University of Liège, B-4000 Liège, Belgium
| | - F Palencia
- CNRS, ICMCB, Université de Bordeaux, UMR 5026, F-33600 Pessac, France
| | - T Pöschel
- Friedrich-Alexander Universität, IMS, D-91052 Erlangen, Germany
| | - J Schockmel
- GRASP, Institute of Physics B5a, University of Liège, B-4000 Liège, Belgium
| | - M Sperl
- Institut für Materialphysik im Weltraum, DLR, D-51170 Köln, Germany
| | - R Stannarius
- IEP, Otto von Guericke Universität, D-39106 Magdeburg, Germany
| | - N Vandewalle
- GRASP, Institute of Physics B5a, University of Liège, B-4000 Liège, Belgium
| | - P Yu
- MSM, University of Twente, 7500 AE Enschede, The Netherlands
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Harth K, Trittel T, Wegner S, Stannarius R. Free Cooling of a Granular Gas of Rodlike Particles in Microgravity. PHYSICAL REVIEW LETTERS 2018; 120:214301. [PMID: 29883145 DOI: 10.1103/physrevlett.120.214301] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Indexed: 06/08/2023]
Abstract
Granular gases as dilute ensembles of particles in random motion are at the basis of elementary structure-forming processes in the Universe, involved in many industrial and natural phenomena, and also excellent models to study fundamental statistical dynamics. The essential difference to molecular gases is the energy dissipation in particle collisions. Its most striking manifestation is the so-called granular cooling, the gradual loss of mechanical energy E(t) in the absence of external excitation. We report an experimental study of homogeneous cooling of three-dimensional granular gases in microgravity. The asymptotic scaling E(t)∝t^{-2} obtained by Haff's minimal model [J. Fluid Mech. 134, 401 (1983)JFLSA70022-112010.1017/S0022112083003419] proves to be robust, despite the violation of several of its central assumptions. The shape anisotropy of the grains influences the characteristic time of energy loss quantitatively but not qualitatively. We compare kinetic energies in the individual degrees of freedom and find a slight predominance of translational motions. In addition, we observe a preferred rod alignment in the flight direction, as known from active matter or animal flocks.
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Affiliation(s)
- Kirsten Harth
- Institute for Experimental Physics, Otto von Guericke University, D-39106 Magdeburg, Germany
| | - Torsten Trittel
- Institute for Experimental Physics, Otto von Guericke University, D-39106 Magdeburg, Germany
| | - Sandra Wegner
- Institute for Experimental Physics, Otto von Guericke University, D-39106 Magdeburg, Germany
| | - Ralf Stannarius
- Institute for Experimental Physics, Otto von Guericke University, D-39106 Magdeburg, Germany
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37
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Deblais A, Barois T, Guerin T, Delville PH, Vaudaine R, Lintuvuori JS, Boudet JF, Baret JC, Kellay H. Boundaries Control Collective Dynamics of Inertial Self-Propelled Robots. PHYSICAL REVIEW LETTERS 2018; 120:188002. [PMID: 29775342 DOI: 10.1103/physrevlett.120.188002] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 02/13/2018] [Indexed: 06/08/2023]
Abstract
Simple ingredients, such as well-defined interactions and couplings for the velocity and orientation of self-propelled objects, are sufficient to produce complex collective behavior in assemblies of such entities. Here, we use assemblies of rodlike robots made motile through self-vibration. When confined in circular arenas, dilute assemblies of these rods act as a gas. Increasing the surface fraction leads to a collective behavior near the boundaries: polar clusters emerge while, in the bulk, gaslike behavior is retained. The coexistence between a gas and surface clusters is a direct consequence of inertial effects as shown by our simulations. A theoretical model, based on surface mediated transport accounts for this coexistence and illustrates the exact role of the boundaries. Our study paves the way towards the control of collective behavior: By using deformable but free to move arenas, we demonstrate that the surface induced clusters can lead to directed motion, while the topology of the surface states can be controlled by biasing the motility of the particles.
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Affiliation(s)
- A Deblais
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - T Barois
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - T Guerin
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - P H Delville
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - R Vaudaine
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - J S Lintuvuori
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - J F Boudet
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - J C Baret
- CNRS, Univ. Bordeaux, CRPP, UPR 8641, 115 Avenue Schweitzer, 33600 Pessac, France
| | - H Kellay
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
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Martín-Gómez A, Levis D, Díaz-Guilera A, Pagonabarraga I. Collective motion of active Brownian particles with polar alignment. SOFT MATTER 2018; 14:2610-2618. [PMID: 29569673 DOI: 10.1039/c8sm00020d] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We present a comprehensive computational study of the collective behavior emerging from the competition between self-propulsion, excluded volume interactions and velocity-alignment in a two-dimensional model of active particles. We consider an extension of the active brownian particles model where the self-propulsion direction of the particles aligns with the one of their neighbors. We analyze the onset of collective motion (flocking) in a low-density regime (10% surface area) and show that it is mainly controlled by the strength of velocity-alignment interactions: the competition between self-propulsion and crowding effects plays a minor role in the emergence of flocking. However, above the flocking threshold, the system presents a richer pattern formation scenario than analogous models without alignment interactions (active brownian particles) or excluded volume effects (Vicsek-like models). Depending on the parameter regime, the structure of the system is characterized by either a broad distribution of finite-sized polar clusters or the presence of an amorphous, highly fluctuating, large-scale traveling structure which can take a lane-like or band-like form (and usually a hybrid structure which is halfway in between both). We establish a phase diagram that summarizes collective behavior of polar active brownian particles and propose a generic mechanism to describe the complexity of the large-scale structures observed in systems of repulsive self-propelled particles.
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Affiliation(s)
- Aitor Martín-Gómez
- Theoretical Soft Matter and Biophysics, Institute of Complex Systems and Institute for Advanced Simulation, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Demian Levis
- CECAM Centre Européen de Calcul Atomique et Moléculaire, École Polytechnique Fédérale de Lausanne, Batochimie, Avenue Forel 2, 1015 Lausanne, Switzerland and University of Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, Barcelona, Spain.
| | - Albert Díaz-Guilera
- University of Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, Barcelona, Spain. and Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès 1, E08028 Barcelona, Spain
| | - Ignacio Pagonabarraga
- CECAM Centre Européen de Calcul Atomique et Moléculaire, École Polytechnique Fédérale de Lausanne, Batochimie, Avenue Forel 2, 1015 Lausanne, Switzerland and University of Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, Barcelona, Spain. and Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès 1, E08028 Barcelona, Spain
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Scholz C, Engel M, Pöschel T. Rotating robots move collectively and self-organize. Nat Commun 2018; 9:931. [PMID: 29500429 PMCID: PMC5834624 DOI: 10.1038/s41467-018-03154-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 01/24/2018] [Indexed: 11/09/2022] Open
Abstract
Biological organisms and artificial active particles self-organize into swarms and patterns. Open questions concern the design of emergent phenomena by choosing appropriate forms of activity and particle interactions. A particularly simple and versatile system are 3D-printed robots on a vibrating table that can perform self-propelled and self-spinning motion. Here we study a mixture of minimalistic clockwise and counter-clockwise rotating robots, called rotors. Our experiments show that rotors move collectively and exhibit super-diffusive interfacial motion and phase separate via spinodal decomposition. On long time scales, confinement favors symmetric demixing patterns. By mapping rotor motion on a Langevin equation with a constant driving torque and by comparison with computer simulations, we demonstrate that our macroscopic system is a form of active soft matter.
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Affiliation(s)
- Christian Scholz
- Institut für Multiscale Simulation, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91052, Erlangen, Germany.
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
| | - Michael Engel
- Institut für Multiscale Simulation, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91052, Erlangen, Germany
| | - Thorsten Pöschel
- Institut für Multiscale Simulation, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91052, Erlangen, Germany
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40
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Levis D, Liebchen B. Micro-flock patterns and macro-clusters in chiral active Brownian disks. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:084001. [PMID: 29309273 DOI: 10.1088/1361-648x/aaa5ec] [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
Chiral active particles (or self-propelled circle swimmers) feature a rich collective behavior, comprising rotating macro-clusters and micro-flock patterns which consist of phase-synchronized rotating clusters with a characteristic self-limited size. These patterns emerge from the competition of alignment interactions and rotations suggesting that they might occur generically in many chiral active matter systems. However, although excluded volume interactions occur naturally among typical circle swimmers, it is not yet clear if macro-clusters and micro-flock patterns survive their presence. The present work shows that both types of pattern do survive but feature strongly enhance fluctuations regarding the size and shape of the individual clusters. Despite these fluctuations, we find that the average micro-flock size still follows the same characteristic scaling law as in the absence of excluded volume interactions, i.e. micro-flock sizes scale linearly with the single-swimmer radius.
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Affiliation(s)
- Demian Levis
- Department 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. CECAM Centre Européen de Calcul Atomique et Moléculaire, École Polytechnique Fédérale de Lausanne, Batochimie, Avenue Forel 2, 1015 Lausanne, Switzerland
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41
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Takatori S, Baba H, Ichino T, Shew CY, Yoshikawa K. Cooperative standing-horizontal-standing reentrant transition for numerous solid particles under external vibration. Sci Rep 2018; 8:437. [PMID: 29323262 PMCID: PMC5765037 DOI: 10.1038/s41598-017-18728-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 12/16/2017] [Indexed: 11/24/2022] Open
Abstract
We report the collective behavior of numerous plastic bolt-like particles exhibiting one of two distinct states, either standing stationary or horizontal accompanied by tumbling motion, when placed on a horizontal plate undergoing sinusoidal vertical vibration. Experimentally, we prepared an initial state in which all of the particles were standing except for a single particle that was placed at the center of the plate. Under continuous vertical vibration, the initially horizontal particle triggers neighboring particles to fall over into a horizontal state through tumbling-induced collision, and this effect gradually spreads to all of the particles, i.e., the number of horizontal particles is increased. Interestingly, within a certain range of vibration intensity, almost all of the horizontal particles revert back to standing in association with the formation of apparent 2D hexagonal dense-packing. Thus, phase segregation between high and low densities, or crystalline and disperse domains, of standing particles is generated as a result of the reentrant transition. The essential features of such cooperative dynamics through the reentrant transition are elucidated with a simple kinetic model. We also demonstrate that an excitable wave with the reentrant transition is observed when particles are situated in a quasi-one-dimensional confinement on a vibrating plate.
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Affiliation(s)
- Satoshi Takatori
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, 610-0394, Japan
| | - Hikari Baba
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, 610-0394, Japan
| | - Takatoshi Ichino
- Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Wakayama, 649-6493, Japan
| | - Chwen-Yang Shew
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.,Department of Chemistry, College of Staten Island, Staten Island, NY, 10314, USA
| | - Kenichi Yoshikawa
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, 610-0394, Japan.
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42
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Patterson GA, Fierens PI, Sangiuliano Jimka F, König PG, Garcimartín A, Zuriguel I, Pugnaloni LA, Parisi DR. Clogging Transition of Vibration-Driven Vehicles Passing through Constrictions. PHYSICAL REVIEW LETTERS 2017; 119:248301. [PMID: 29286724 DOI: 10.1103/physrevlett.119.248301] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Indexed: 06/07/2023]
Abstract
We report experimental results on the competitive passage of elongated self-propelled vehicles rushing through a constriction. For the chosen experimental conditions, we observe the emergence of intermittencies similar to those reported previously for active matter passing through narrow doors. Noteworthy, we find that, when the number of individuals crowding in front of the bottleneck increases, there is a transition from an unclogged to a clogged state characterized by a lack of convergence of the mean clog duration as the measuring time increases. It is demonstrated that this transition-which was reported previously only for externally vibrated systems such as colloids or granulars-appears also for self-propelled agents. This suggests that the transition should also occur for the flow through constrictions of living agents (e.g., humans and sheep), an issue that has been elusive so far in experiments due to safety risks.
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Affiliation(s)
- G A Patterson
- Instituto Tecnológico de Buenos Aires, CONICET, Lavardén 315, 1437 C. A. de Buenos Aires, Argentina
| | - P I Fierens
- Instituto Tecnológico de Buenos Aires, CONICET, Lavardén 315, 1437 C. A. de Buenos Aires, Argentina
| | - F Sangiuliano Jimka
- Instituto Tecnológico de Buenos Aires, Lavardén 315, 1437 C. A. de Buenos Aires, Argentina
| | - P G König
- Instituto Tecnológico de Buenos Aires, Lavardén 315, 1437 C. A. de Buenos Aires, Argentina
| | - A Garcimartín
- Departamento de Física y Matemática Aplicada, Facultad de Ciencias, Universidad de Navarra, Pamplona 31080, Spain
| | - I Zuriguel
- Departamento de Física y Matemática Aplicada, Facultad de Ciencias, Universidad de Navarra, Pamplona 31080, Spain
| | - L A Pugnaloni
- Departamento de Ingeniería Mecánica, Facultad Regional La Plata, Universidad Tecnológica Nacional, CONICET, Avenida 60 Esq. 124, 1900 La Plata, Argentina
| | - D R Parisi
- Instituto Tecnológico de Buenos Aires, CONICET, Lavardén 315, 1437 C. A. de Buenos Aires, Argentina
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Karbowniczek P, Chrzanowska A. Kinetic-contact-driven gigantic energy transfer in a two-dimensional Lennard-Jones fluid confined to a rotating pore. Phys Rev E 2017; 96:053113. [PMID: 29347671 DOI: 10.1103/physreve.96.053113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Indexed: 06/07/2023]
Abstract
A two-dimensional Lennard-Jones system in a circular and rotating container has been studied by means of molecular dynamics technique. A nonequilibrium transition to the rotating stage has been detected in a delayed time since an instant switching of the frame rotation. This transition is attributed to the increase of the density at the wall because of the centrifugal force. At the same time the phase transition occurs, the inner system changes its configuration of the solid-state type into the liquid type. Impact of angular frequency and molecular roughness on the transport properties of the nonrotating and rotating systems is analyzed.
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Affiliation(s)
- Paweł Karbowniczek
- Institute of Physics, Cracow University of Technology, ul. Podchorążych 1, 30-084 Kraków, Poland
| | - Agnieszka Chrzanowska
- Institute of Physics, Cracow University of Technology, ul. Podchorążych 1, 30-084 Kraków, Poland
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