Lattice-Boltzmann simulation of free nematic-isotropic interfaces

Coelho, Rodrigo C. V.; Araújo, Nuno A. M.; Gama, M. M. Telo da

doi:10.1051/epjconf/202023302001

Cited by 5 publications

(3 citation statements)

References 12 publications

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“…This system of differential equations is solved using a hybrid method with the same spatial discretization: equation (2.2) is solved using finite-differences and equations (2.3) and (2.4) are recovered in the macroscopic limit with the lattice Boltzmann method. The method is similar to those used in [8,16,17] and, for simplicity, we use the single relaxation time approximation in the Boltzmann equation [18,19]. Our results are given in units such that the distance between nodes is normalΔx=1 and the time step is normalΔt=1 (lattice units).…”

Section: Methodsmentioning

confidence: 99%

Director alignment at the nematic–isotropic interface: elastic anisotropy and active anchoring

Coelho

Araújo

Gama

2021

Phil. Trans. R. Soc. A.

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Activity in nematics drives interfacial flows that lead to preferential alignment that is tangential or planar for extensile systems (pushers) and perpendicular or homeotropic for contractile ones (pullers). This alignment is known as active anchoring and has been reported for a number of systems and described using active nematic hydrodynamic theories. The latter are based on the one-elastic constant approximation, i.e. they assume elastic isotropy of the underlying passive nematic. Real nematics, however, have different elastic constants, which lead to interfacial anchoring. In this paper, we consider elastic anisotropy in multiphase and multicomponent hydrodynamic models of active nematics and investigate the competition between the interfacial alignment driven by the elastic anisotropy of the passive nematic and the active anchoring. We start by considering systems with translational invariance to analyse the alignment at flat interfaces and, then, consider two-dimensional systems and active nematic droplets. We investigate the competition of the two types of anchoring over a wide range of the other parameters that characterize the system. The results of the simulations reveal that the active anchoring dominates except at very low activities, when the interfaces are static. In addition, we found that the elastic anisotropy does not affect the dynamics but changes the active length that becomes anisotropic. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

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Section: Methodsmentioning

confidence: 99%

Director alignment at the nematic–isotropic interface: elastic anisotropy and active anchoring

Coelho

Araújo

Gama

2021

Phil. Trans. R. Soc. A.

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“…The numerical method is similar to those used in Refs. [17,42,43] and, for simplicity, we use the single relaxation time approximation in the Boltzmann equation [41,44].…”

Section: Methodsmentioning

confidence: 99%

Active nematics on flat surfaces: from droplet motility and scission to active wetting

Coelho¹,

Figueiredo²,

Gama³

2023

Preprint

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We consider the dynamics of active nematics droplets on flat surfaces, based on the continuum hydrodynamic theory. We investigate a wide range of dynamical regimes as a function of the activity and droplet size on surfaces characterized by strong anchoring and a range of equilibrium contact angles. The activity was found to control a variety of dynamical regimes, including the selfpropulsion of droplets on surfaces, scission, active wetting and droplet evaporation. Furthermore, we found that on a given surface (characterized by the anchoring and the equilibrium contact angle) the dynamical regimes may be controlled by the active capillary number of suspended droplets. We also found that the active nematics concentration of the droplets varies with the activity, affecting the wetting behaviour weakly but ultimately driving droplet evaporation. Our analysis provides a global description of a wide range of dynamical regimes reported for active nematics droplets and suggests a unified description of droplets on surfaces. We discuss the key role of the finite size of the droplet and comment on the suppression of these regimes in the infinite size limit, where the active nematics is turbulent at any degree of activity.

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“…The method is similar to those used in Refs. [8,14,15] and, for simplicity, we use the single relaxation time approximation in the Boltzmann equation [16,17]. Our results are given in units such that the distance between nodes is ∆x = 1 and the time step is ∆t = 1 (lattice units).…”

Section: (A) Multiphase Modelmentioning

confidence: 99%

Director alignment at the nematic-isotropic interface: elastic anisotropy and active anchoring

Coelho,

Araújo,

da Gama

2020

Preprint

Self Cite

View full text Add to dashboard Cite

Activity in nematics drives interfacial flows that lead to preferential alignment that is tangential or planar for extensile systems (pushers) and perpendicular or homeotropic for contractile ones (pullers). This alignment is known as active anchoring and has been reported for a number of systems and described using active nematic hydrodynamic theories. The latter are based on the one-elastic constant approximation, i.e., they assume elastic isotropy of the underlying passive nematic. Real nematics, however, have different elastic constants, which lead to interfacial anchoring. In this paper, we consider elastic anisotropy in multiphase and multicomponent hydrodynamic models of active nematics and investigate the competition between the interfacial alignment driven by the elastic anisotropy of the passive nematic and the active anchoring. We start by considering systems with translational invariance to analyze the alignment at flat interfaces and, then, consider two-dimensional systems and active nematic droplets. We investigate the competition of the two types of anchoring over a wide range of the other parameters that characterize the system. The results of the simulations reveal that the active anchoring dominates except at very low activities, when the interfaces are static. In addition, we found that the elastic anisotropy does not affect the dynamics but changes the active length that becomes anisotropic.

show abstract

Lattice-Boltzmann simulation of free nematic-isotropic interfaces

Cited by 5 publications

References 12 publications

Director alignment at the nematic–isotropic interface: elastic anisotropy and active anchoring

Director alignment at the nematic–isotropic interface: elastic anisotropy and active anchoring

Active nematics on flat surfaces: from droplet motility and scission to active wetting

Director alignment at the nematic-isotropic interface: elastic anisotropy and active anchoring

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