Orientational Correlations in Active and Passive Nematic Defects

Pearce, Daniel J.; Nambisan, Jyothishraj; Ellis, Perry W.; Fernández‐Nieves, Alberto; Giomi, Luca

doi:10.1103/physrevlett.127.197801

Cited by 21 publications

(30 citation statements)

References 44 publications

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“…It only took an energy injection at the smallest scale, independent from spin to spin, for the BKT scenario of the XY model to collapse. As it shows that long-range influence is lost as soon as the model is made active, the present work conceptually supports the conclusions of Pearce et al [50], where they report the absence of long-range ordering of defects in active nematics.…”

Section: The Fate Of the Bkt Transitionsupporting

confidence: 92%

Dynamics of Topological Defects in the noisy Kuramoto Model in two dimensions

Rouzaire¹,

Levis²

2022

Preprint

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We consider the two-dimensional (2D) noisy Kuramoto model of synchronization with shortrange coupling and a Gaussian distribution of intrinsic frequencies, and investigate its ordering dynamics following a quench. We consider both underdamped (inertial) and over-damped dynamics, and show that the long-term properties of this intrinsically out-of-equilibrium system do not depend on the inertia of individual oscillators. The model does not exhibit any phase transition as its correlation length remains finite, scaling as the inverse of the standard deviation of the distribution of intrinsic frequencies. The quench dynamics proceeds via domain growth, with a characteristic length that initially follows the growth law of the 2D XY model, although is not given by the mean separation between defects. Topological defects are generically free, breaking the Berezinskii-Kosterlitz-Thouless scenario of the 2D XY model. Vortices perform a random walk reminiscent of the self-avoiding random walk, advected by the dynamic network of boundaries between synchronised domains; featuring long-time super-diffusion, with the anomalous exponent α = 3/2.

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Section: The Fate Of the Bkt Transitionsupporting

confidence: 92%

Dynamics of Topological Defects in the noisy Kuramoto Model in two dimensions

Rouzaire¹,

Levis²

2022

Preprint

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“…The dimensional version of the model ( 11)-( 13) contains only two material parameters -the activity coefficient α and the effective viscosity µ -which define a time scale, but not a length scale. The absence of a characteristic length scale is consistent with the observed power law scaling of vortex number density [12] and orientational correlations [48]. The absence of elastic stresses in our model suggests that, at larger separations, interaction between topological defects is mediated by the flow.…”

Section: Limitations and Future Worksupporting

confidence: 87%

“…Imaging is done using 10× and 20× objectives to focus on regions with area on the order of mm 2 , away from the edges of the flow cell. The imaging process results in a time series of 8-bit grayscale images, which are stored as the raw data [48].…”

Section: Experimental Setup and Data Acquisitionmentioning

confidence: 99%

Physically-informed data-driven modeling of active nematics

Golden¹,

Grigoriev²,

Nambisan³

et al. 2022

Preprint

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A continuum description is essential for understanding variety of collective phenomena in active matter. However, building quantitative continuum models of active matter from first principles can be extremely challenging due to both the gaps in our knowledge and the complicated structure of nonlinear interactions. Here we use a novel physically-informed data-driven approach to construct a complete mathematical model of an active nematic from experimental data describing kinesin-drive microtubule bundles confined to an oil-water interface. We find that the structure of the model is similar to the Leslie-Erisken and Beris-Edwards models, but there are notable differences. Rather unexpectedly, elastic effects are found to play no role, with the dynamics controlled entirely by the balance between active stresses and highly anisotropic viscous stresses.

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“…which takes values of ±1/2 at the defect cores and is zero otherwise. The angle θ is calculated using ∇ • Q = (cos θ, sin θ), where ∇ • Q gives the direction of the defects self-propulsion [64] that for extensile systems (ζ 1 > 0) is from tail to head of the +1/2 defect. Interestingly, in this phase, the defects in each flock move in the same direction and show polar order, but different defect flocks can migrate in antiparallel directions within the system as seen from the snapshots in Fig.…”

Section: Iii2 Dynamic Phasesmentioning

confidence: 99%