Hydrodynamics, superfluidity, and giant number fluctuations in a model of self-propelled particles

Chakraborty, Tanmoy; Chakraborti, Subhadip; Das, Arghya Kusum; Pradhan, Punyabrata

doi:10.1103/physreve.101.052611

Cited by 13 publications

(12 citation statements)

References 52 publications

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“…We go beyond previous studies by deriving the cluster and gap distributions for moderate and large tumble rates in the Independent Interval Approximation, and also in deducing the timedependent behavior for small tumble rates. Other mass transport models have previous been studied in order to calculate various thermodynamic and hydrodynamic quantities, such as the chemical potential [43] and the transport coefficients [20,44]. We shall see that for moderate tumble rates, these approaches give results which are well supported by numerical simulations.…”

Section: Introductionmentioning

confidence: 70%

“…where σ 2 (ρ) is the single-site mass fluctuations. To derive the hydrodynamic equations for the mass model, we consider the current across a bond in presence of a small density gradient ∂ρ/∂x, and in presence of a small field of strength F 1, that couples to the mass [20,44,54]. In the presence of a field, particles hop to the right with rate 1 + F and to the left with rate 1 − F .…”

Section: Hydrodynamics For Large η: Mean Field Approximationmentioning

confidence: 99%

“…These systems, widely known as active matter, have been studied through different simple non-equilibrium models. Examples include Vicsek models [7][8][9] with alignment interaction to study flocks of birds, active Brownian particles [10,11] and run and tumble particles (RTPs) [12,13] to describe the interacting micro-organisms in a liquid medium, and active lattice gases [14][15][16][17][18][19][20]; for reviews see Refs. [21,22].…”

Section: Introductionmentioning

confidence: 99%

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Hard core run and tumble particles on a one dimensional lattice

Dandekar,

Chakraborti,

Rajesh

2020

Preprint

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We study the large scale behavior of a collection of hard core run and tumble particles on a one dimensional lattice with periodic boundary conditions. Each particle has persistent motion in one direction decided by an associated spin variable until the direction of spin is reversed. We map the run and tumble model to a mass transfer model with fluctuating directed bonds. We calculate the steady state single site mass distribution in the mass model within a mean field approximation for larger spin-flip rates and by analyzing an appropriate coalescence fragmentation model for small spin-flip rates. We also calculate the hydrodynamic coefficients of diffusivity and conductivity for both large and small spin-flip rates and show that the Einstein relation is violated in both regimes. We also show how the non-gradient nature of the process can be taken into account in a systematic manner to calculate the hydrodynamic coefficients.

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Section: Introductionmentioning

confidence: 70%

Section: Hydrodynamics For Large η: Mean Field Approximationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hard core run and tumble particles on a one dimensional lattice

Dandekar,

Chakraborti,

Rajesh

2020

Preprint

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“…Note that, while the conductivity diverges near criticality, the bulk-diffusion coefficient remains finite. This implies that the condensation transition is facilitated not by vanishing diffusivity, but rather by a huge (in fact, singular) enhancement in the mobility of masses, as observed in a mass transport process studied in the context of selfpropelled particles [30]. Following the approach in Sec.…”

Section: Transport Coefficients and Einstein Relationmentioning

confidence: 94%

“…Later, it has been used to derive hydrodynamics for various conserved-mass transport processes that manifestly violate detailed balance at the microscopic level [27,28]. In a more recent development, large-scale hydrodynamics has been derived for systems having a generalized gradient property [29,30]. The mass aggregation models considered in this paper have gradient property, which, along with a hypothesis of the existence of a local steady state -analogous to the previously mentioned local equilibrium hypothesis, can be used to calculate the transport coefficients.…”

Section: Hydrodynamics: Theoretical Frameworkmentioning

confidence: 99%

Transport and fluctuations in mass aggregation processes: mobility driven clustering

Chakraborti,

Chakraborty,

Das

et al. 2020

Preprint

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We calculate the bulk-diffusion coefficient and the conductivity in a broad class of conserved-mass aggregation processes on a ring of discrete sites. These processes involve chipping and fragmentation of masses, which diffuse around and aggregate upon contact with their neighboring masses. We find that, even in the absence of microscopic time reversibility, the systems satisfy an Einstein relation, which connects the ratio of the conductivity and the bulk-diffusion coefficient to mass fluctuation. Interestingly, when aggregation dominates over chipping, the conductivity or, equivalently, the mobility, gets enhanced. The enhancement in conductivity, in accordance with the Einstein relation, results in large mass fluctuations, implying a mobility driven clustering in the system. Indeed, in a certain parameter regime, we demonstrate that the conductivity diverges beyond a critical density, signaling the onset of a condensation transition observed in the past. In a striking similarity to Bose-Einstein condensation, the condensate formation along with the diverging conductivity thus underlies a dynamic "superfluidlike" transition in these nonequilibrium systems. Notably, the bulkdiffusion coefficient remains finite in all cases. Our analytic results are in a quite good agreement with simulations.

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Density fluctuations of two-dimensional active-passive mixtures

Zhang

Huang

et al. 2022

Commun. Theor. Phys.

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Dimension-dependent giant density fluctuations are a typical feature of active matter systems. In this work, we study the density fluctuation in two-dimensional mixtures of active and passive particles by Brownian dynamics simulations. The boundary of motility induced phase separation is determined by the tansition from unimodal to bimodal density distribution. A rapid increase of the fluctuation exponent near the boundary of phase separation in the plane of density and P\'eclet number was observed. When phase separation occurs, the fluctuation exponent is an approximate constant of $0.85$.

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Hydrodynamics, superfluidity, and giant number fluctuations in a model of self-propelled particles

Cited by 13 publications

References 52 publications

Hard core run and tumble particles on a one dimensional lattice

Hard core run and tumble particles on a one dimensional lattice

Transport and fluctuations in mass aggregation processes: mobility driven clustering

Density fluctuations of two-dimensional active-passive mixtures

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