Coherent motion of dense active matter

Doostmohammadi, Amin; Yeomans, J. M.

doi:10.1140/epjst/e2019-700109-x

Cited by 34 publications

(29 citation statements)

References 62 publications

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“…Of particular interest is the characterization of ABP in the dense regime, see e.g. spontaneous flow [25] or glassy behaviour [54,75] in biological tissues, biofilms, cell monolayers [6,37], and can be considered a target for the development of new materials [78]. In two dimensions (2D), ABP present ordering phase transitions when the density of the system is increased [14,23,24,46], which are connected to those encountered for passive hard colloids [5,42,74].…”

Section: Introductionmentioning

confidence: 99%

Inertial and hydrodynamic effects on the liquid-hexatic transition of active colloids

Negro¹,

Caporusso²,

Digregorio³

et al. 2022

Preprint

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We study numerically the role of inertia and hydrodynamics in the liquid-hexatic transition of active colloids at intermediate activity, where motility induced phase separation (MIPS) does not occur. We show that in the case of active Brownian particles (ABP), the critical density of the transition decreases upon increasing the particle's mass, suggesting that inertia has an effect of promoting hexatic ordering, contrary to self-propulsion which has the opposite effect in the activity regime considered. Active hydrodynamic particles (AHP), instead, undergo the liquid-hexatic transition at higher values of packing fraction φ than the corresponding ABP, suggesting that hydrodynamics have the net effect of disordering the system. At increasing densities, close to the hexatic-liquid transition, we found in the case of AHP the appearance of self-sustained organized motion with clusters of particles moving coherently.

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Section: Introductionmentioning

confidence: 99%

Inertial and hydrodynamic effects on the liquid-hexatic transition of active colloids

Negro¹,

Caporusso²,

Digregorio³

et al. 2022

Preprint

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“…Simulations of these [32,33] and related flows in annuli and channels are reviewed in Ref. [34]. Studies of 3D active fluids in toroidal channels and cylinders (with flows parallel to the cylinder surface) [35] revealed a transition between turbulent motion and coherent flow.…”

Section: Introductionmentioning

confidence: 99%

Macroscopic rotation of active colloids in a colloid-polymer mixture confined inside a spherical cavity

Bera¹,

Binder²,

Егоров³

et al. 2021

Preprint

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From studies via Molecular Dynamics simulations, we report results on structure and dynamics in mixtures of active colloids and passive polymers that are confined inside a spherical container with a repulsive boundary. Such systems mimic the presence of bacteria in the background of bio-polymers. All interactions in the fully passive case are chosen in such a way that in equilibrium coexistence between colloid-rich and polymer-rich phases occurs. For most part of the studies the chosen compositions give rise to Janus structure; one side of the sphere is occupied by the colloids and the rest by the polymers. This partially wet situation mimics nearly a neutral wall in the fully passive scenario. Following the introduction of a velocity-aligning activity to the colloids, the shape of the polymer-rich domain changes to that of an ellipsoid, around the long axis of which the colloid-rich domain attains a macroscopic angular momentum. In the steady state, the orientation of this axis evolves via diffusion, implying that the passive domain is set into motion as well by the active particles.

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“…Active matter 1 – 4 has recently become a topical area of research in soft matter physics. Much effort has been spent to understand the underlying non equilibrium mechanisms that rule the dynamics of systems where constituents are actively capable of converting internal energy into work.…”

Section: Introductionmentioning

confidence: 99%

Soft channel formation and symmetry breaking in exotic active emulsions

Carenza

Gonnella

Lamura³

et al. 2020

Sci Rep

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We use computer simulations to study the morphology and rheological properties of a bidimensional emulsion resulting from a mixture of a passive isotropic fluid and an active contractile polar gel, in the presence of a surfactant that favours the emulsification of the two phases. By varying the intensity of the contractile activity and of an externally imposed shear flow, we find three possible morphologies. For low shear rates, a simple lamellar state is obtained. For intermediate activity and shear rate, an asymmetric state emerges, which is characterized by shear and concentration banding at the polar/isotropic interface. A further increment in the active forcing leads to the self-assembly of a soft channel where an isotropic fluid flows between two layers of active material. We characterize the stability of this state by performing a dynamical test varying the intensity of the active forcing and shear rate. Finally, we address the rheological properties of the system by measuring the effective shear viscosity, finding that this increases as active forcing is increased—so that the fluid thickens with activity.

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Coherent motion of dense active matter

Cited by 34 publications

References 62 publications

Inertial and hydrodynamic effects on the liquid-hexatic transition of active colloids

Inertial and hydrodynamic effects on the liquid-hexatic transition of active colloids

Macroscopic rotation of active colloids in a colloid-polymer mixture confined inside a spherical cavity

Soft channel formation and symmetry breaking in exotic active emulsions

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