Spatiotemporal Rheochaos in Nematic Hydrodynamics

Chakrabarti, Buddhapriya; Das, Moumita; Dasgupta, Chandan; Ramaswamy, Sriraṁ; Sood, A. K.

doi:10.1103/physrevlett.92.055501

Cited by 54 publications

(67 citation statements)

References 25 publications

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“…Our model exhibits spatio-temporal chaos. The corresponding space-time patterns are varied, but fall into a common picture (coherent with that of other groups [32,33]): rheochaos manifests as a flow that restlessly attempts to form steady shear bands, but fails due to internal structural constraints.…”

Section: Discussionmentioning

confidence: 85%

“…The results we have presented so far, along with other works [27,32,33], might be taken to suggest a generic interpretation of rheochaos in complex fluids as resulting from the erratic motion of discrete interfaces between shear bands. This idea is appealing because, in turn, it suggests that rheochaos may be more efficiently modelled by focussing on interfacial dynamics and writing an equation of motion directly for the interface [27,56] (rather than for the whole fluid as we are doing here).…”

Section: Low-order Resultsmentioning

confidence: 93%

“…32 have demonstrated the presence of a rich dynamics, including rheochaos, in their model. Also closely related is the work by Chakrabarti et al [33] on nematic liquid crystals which also shows regimes of spatiotemporal chaos. In what follows, we shall note similarities and differences between our own work and these other studies.…”

Section: Introductionmentioning

confidence: 99%

“…Our numerical scheme expands the stress in Fourier modes, then is solving for the evolution of these-rather than directly solving the model equation on a grid of points in direct space [32,33]. Such a spectral scheme [50] had two main advantages, as follows: (a) in Fourier space, working under conditions of fixed mean stress simply corresponds to fixing the value of the uniform, zeroth mode in the Fourier expansion of the stress (this is much more difficult to implement in direct-space schemes); (b) Not only can arbitrarily accurate numerical results be obtained by keeping enough Fourier modes in the scheme ('high-order truncation'), but also, by keeping only a minimal number of modes ('low-order truncation'), one can obtain a reduced description whose analysis is much simplified.…”

Section: A Spectral Scheme; Boundary Conditionsmentioning

confidence: 99%

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Minimal model for chaotic shear banding in shear thickening fluids

Aradian

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2006

Phys. Rev. E

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We present a minimal model for spatiotemporal oscillation and rheochaos in shear-thickening complex fluids at zero Reynolds number. In the model, a tendency towards inhomogeneous flows in the form of shear bands combines with a slow structural dynamics, modelled by delayed stress relaxation. Using Fourier-space numerics, we study the nonequilibrium 'phase diagram' of the fluid as a function of a steady mean (spatially averaged) stress, and of the relaxation time for structural relaxation. We find several distinct regions of periodic behavior (oscillating bands, travelling bands, and more complex oscillations) and also regions of spatiotemporal rheochaos. A low-dimensional truncation of the model retains the important physical features of the full model (including rheochaos) despite the suppression of sharply defined interfaces between shear bands. Our model maps onto the FitzHugh-Nagumo model for neural network dynamics, with an unusual form of long-range coupling.

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Section: Discussionmentioning

confidence: 85%

Section: Low-order Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: A Spectral Scheme; Boundary Conditionsmentioning

confidence: 99%

See 2 more Smart Citations

Minimal model for chaotic shear banding in shear thickening fluids

Aradian

Cates

2006

Phys. Rev. E

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“…This includes transitions to stable statically distorted deformations of the director field (Freedericksz transition [7]), shear banding [8], and even the onset of turbulent and chaotic behavior in the presence of shear [9]. Active liquid crystals exhibit a similar wealth of phenomena due to internal forcing, i.e., spontaneously.…”

mentioning

confidence: 99%

Complex Spontaneous Flows and Concentration Banding in Active Polar Films

2008

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We study the dynamical properties of active polar liquid crystalline films. Like active nematic films, active polar films undergo a dynamical transitions to spontaneously flowing steady-states. Spontaneous flow in polar fluids is, however, always accompanied by strong concentration inhomogeneities or "banding" not seen in nematics. In addition, a spectacular property unique to polar active films is their ability to generate spontaneously oscillating and banded flows even at low activity. The oscillatory flows become increasingly complicated for strong polarity.

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Anisotropy and Dynamic Ranges in Effective Properties of Sheared Nematic Polymer Nanocomposites

Forest

Zheng²,

Zhou

et al. 2005

Adv Funct Materials

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Nematic, or liquid‐crystalline, polymer nanocomposites (NPNCs) are composed of large aspect ratio, rod‐like or platelet, rigid macromolecules in a matrix or solvent, which itself may be aqueous or polymeric. NPNCs are engineered for high‐performance material applications, ranging across mechanical, electrical, piezoelectric, thermal, and barrier properties. The rods or platelets possess enormous property contrasts relative to the solvent, yet the composite properties are strongly affected by the orientational distribution of the nanophase. Nematic polymer film processing flows are shear‐dominated, for which orientational distributions are well known to be highly sensitive to shear rate and volume fraction of the nematogens, with unsteady response being the most expected outcome at typical low shear rates and volume fractions. The focus of this article is a determination of the ranges of anisotropy and dynamic fluctuations in effective properties arising from orientational probability distribution functions generated by steady shear of NPNC monodomains. We combine numerical databases for sheared monodomain distributions[1,2] of thin rod or platelet dispersions together with homogenization theory for low‐volume‐fraction spheroidal inclusions[3] to calculate effective conductivity tensors of steady and oscillatory sheared mesophases. We then extract maximum scalar conductivity enhancement and anisotropy for each type of sheared monodomain (flow‐aligned, tumbling, kayaking, and chaotic).

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Spatiotemporal Rheochaos in Nematic Hydrodynamics

Cited by 54 publications

References 25 publications

Minimal model for chaotic shear banding in shear thickening fluids

Minimal model for chaotic shear banding in shear thickening fluids

Complex Spontaneous Flows and Concentration Banding in Active Polar Films

Anisotropy and Dynamic Ranges in Effective Properties of Sheared Nematic Polymer Nanocomposites

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