Soft channel formation and symmetry breaking in exotic active emulsions

Carenza, Livio Nicola; Gonnella, Giuseppe; Lamura, A.; Marenduzzo, Davide; Negro, Giuseppe; Tiribocchi, Adriano

doi:10.1038/s41598-020-72742-9

Cited by 17 publications

(13 citation statements)

References 45 publications

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“…(2.8) and (2.9) by a standard lattice Boltzmann method [45]. We incidentally note that, although a hybrid LB machinery has been already successfully employed to study binary [52] and ternary fluids [49], active gels [53][54][55] and liquid crystals, such as nematics [56,57] and cholesterics [30,31,[58][59][60][61], in this work the applicability of the method has been further extended to study liquid crystal emulsions in the presence of a surfactant whose dynamics is explicitly solved.…”

Section: Numerical Implementationmentioning

confidence: 99%

Lattice Boltzmann Modeling of Cholesteric Liquid Crystal Droplets Under an Oscillatory Electric Field

F.¹,

null²,

A.³

2023

CICP

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We numerically study the dynamics of quasi-two dimensional cholesteric liquid crystal droplets in the presence of a time-dependent electric field, rotating at constant angular velocity. A surfactant sitting at the droplet interface is also introduced to prevent droplet coalescence. The dynamics is modeled following a hybrid numerical approach, where a standard lattice Boltzmann technique solves the Navier-Stokes equation and a finite difference scheme integrates the evolution equations of liquid crystal and surfactant. Our results show that, once the field is turned on, the liquid crystal rotates coherently triggering a concurrent orbital motion of both droplets around each other, an effect due to the momentum transfer to the surrounding fluid. In addition the topological defects, resulting from the conflict orientation of the liquid crystal within the drops, exhibit a chaotic-like motion in cholesterics with a high pitch, in contrast with a regular one occurring along circular trajectories observed in nematics drops. Such behavior is found to depend on magnitude and frequency of the applied field as well as on the anchoring of the liquid crystal at the droplet interface. These findings are quantitatively evaluated by measuring the angular velocity of fluid and drops for various frequencies of the applied field.

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Section: Numerical Implementationmentioning

confidence: 99%

Lattice Boltzmann Modeling of Cholesteric Liquid Crystal Droplets Under an Oscillatory Electric Field

F.¹,

null²,

A.³

2023

CICP

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“…Interestingly, this behaviour is similar to travelling bands occurring in Vicsek-like models [72,73], where an additional alignment interaction of active force directions is introduced, which allows particles to move coherently. Velocity correlations between particles have also been found in systems of ABP with different persistence times [74][75][76][77], flowing crystals made of spontaneously aligning self-propelled hard disks [78] and self-sustained spontaneous flows in active gels [79][80][81][82][83].…”

Section: Self Sustained Motion At High Densitymentioning

confidence: 99%

Hydrodynamic effects on the liquid-hexatic transition of active colloids

Negro

Digregorio

et al. 2022

Eur. Phys. J. E

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We study numerically the role of 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, enhancing ordering, while self-propulsion 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 $$\phi $$ 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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“…In particular, we shall here consider a system of multiple active polar droplets emulsified in a passive isotropic background sheared between two moving walls. The system that we consider [34][35][36][37][38] has the property that a tunable amount of active material can be homogeneously dispersed in an emulsion. Importantly, the two components have the same nominal viscosity, so that the observed rheological behaviors uniquely result from the complexity introduced by the mutual effect of interfaces, liquid crystalline phase and activity.…”

Section: Introductionmentioning

confidence: 99%

Rheology of active emulsions with negative effective viscosity

et al. 2021

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We numerically study by lattice Boltzmann simulations the rheological properties of an active emulsion made of a suspension of an active polar gel embedded in an isotropic passive background. We find that the hexatic equilibrium configuration of polar droplets is highly sensitive to both active injection and external forcing and may either lead to asymmetric unidirectional states which break top-bottom symmetry or symmetric ones. In this latter case, for large enough activity, the system develops a shear thickening regime at low shear rates. Importantly, for larger external forcing a regime with stable negative effective viscosity is found. Moreover, at intermediate activity a region of multistability is encountered and we show that a maximum entropy production principle holds in selecting the most favorable state.

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Soft channel formation and symmetry breaking in exotic active emulsions

Cited by 17 publications

References 45 publications

Lattice Boltzmann Modeling of Cholesteric Liquid Crystal Droplets Under an Oscillatory Electric Field

Lattice Boltzmann Modeling of Cholesteric Liquid Crystal Droplets Under an Oscillatory Electric Field

Hydrodynamic effects on the liquid-hexatic transition of active colloids

Rheology of active emulsions with negative effective viscosity

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