Generic Conditions for Hydrodynamic Synchronization

Uchida, Nozomu; Golestanian, Ramin

doi:10.1103/physrevlett.106.058104

Cited by 167 publications

(236 citation statements)

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“…This equation is correct to O(γ/(d 3 sin δ)) [28,34]. In this form, the hydrodynamic coupling becomes isotropic and our system resembles existing models of non-locally coupled oscillators with phase delay [29,30].…”

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confidence: 92%

“…Our model reproduced the enhancement of orientational ordering, while it predicts global ordering and not the finite-size correlation as observed in the experiments. The experimental patterns might be explained by some kind of frozen disorder in the flagellar configuration, which can be readily incorporated in our model [34,35]. The case of δ = 90 • is realized by rigid spheres without pumping.…”

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confidence: 99%

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Synchronization and Collective Dynamics in a Carpet of Microfluidic Rotors

2010

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We study synchronization of an array of rotors on a substrate that are coupled by hydrodynamic interaction. Each rotor, which is modeled by an effective rigid body, is driven by an internal torque and exerts an active force on the surrounding fluid. The long-ranged nature of the hydrodynamic interaction between the rotors causes a rich pattern of dynamical behaviors including phase ordering and self-proliferating spiral waves. Our results suggest strategies for designing controllable microfluidic mixers using the emergent behavior of hydrodynamically coupled active components. PACS numbers: 87.19.rh,07.10.Cm,47.61.Ne,87.80.Fe,87.85.Qr Introduction. Microorganisms and the mechanical components of the cell motility machinery such as cilia and flagella operate in low Reynolds number conditions where hydrodynamics is dominated by viscous forces [1]. The medium thus induces a long-ranged hydrodynamic interaction between these active objects, which could lead to emergent many-body behaviors. Examples of such cooperative dynamical effects include sperms beating in harmony [2], metachronal waves in cilia [3][4][5], formation of bound states between rotating microorganisms [6], and flocking behavior of red blood cells moving in a capillary [7]. For a collection of free swimmers, such as microorganisms [8], hydrodynamic interactions have been shown to lead to instabilities [9,10] that can result in complex dynamical behaviors [10,11]. In the context of simple microswimmer models where hydrodynamic interactions coupled to internal degrees of freedom can be studied with minimal complexity, it has been shown that the coupling could result in complex dynamical behaviors such as oscillatory bound states between two swimmers [12], and collective many-body swimming phases [13,14].A particularly interesting aspect of such hydrodynamic coupling is the possibility of synchronization between different objects with cyclic motions [4,5,[15][16][17][18][19][20][21]. This effect has mostly been studied in simple systems such as two interacting objects or linear arrays and very little is known about possible many-body emergent behaviors of a large number of active objects with hydrodynamic coupling. For example, in a recent experiment [22], Darnton et al. observed chaotic flow patterns with complex vortices above a carpet of bacteria with their heads attached to a substrate and their flagella free to interact with the fluid (see also [23]). On the other hand, recent advances from micron-scale magnetically actuated tails [24] to synthetic molecular rotors [25] now allow fabrication of arrays of active tails that can stir up the fluid. It is therefore very important to explore the possible complexity of the phase behavior of such an actively stirred microfluidic system.Here, we consider a simple generic model of rotors [26] positioned on a regular 2D array on a substrate and study

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confidence: 92%

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confidence: 99%

Synchronization and Collective Dynamics in a Carpet of Microfluidic Rotors

2010

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“…The result, shown in figure 13 is that indeed the flow field can be accurately captured by a Stokeslet moving on an orbit, but not surprisingly there are significant variations in the magnitude through the beat period. And indeed, as pointed out by Uchida & Golestanian (2011, 2012, beating synchrony can arise not only from orbital compliance with fixed internal forcing, but also by variations in internal forcing along fixed orbits. Elegant experimental studies with colloidal oscillators (Brout & Cicuta 2016) probe in detail the competition between these effects.…”

Section: R E Goldsteinmentioning

confidence: 99%

Batchelor Prize Lecture Fluid dynamics at the scale of the cell

Goldstein

2016

J. Fluid Mech.

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The world of cellular biology provides us with many fascinating fluid dynamical phenomena that lie at the heart of physiology, development, evolution and ecology. Advances in imaging, micromanipulation and microfluidics over the past decade have made possible high-precision measurements of such flows, providing tests of microhydrodynamic theories and revealing a wealth of new phenomena calling out for explanation. Here I summarize progress in four areas within the field of 'active matter': cytoplasmic streaming in plant cells, synchronization of eukaryotic flagella, interactions between swimming cells and surfaces and collective behaviour in suspensions of microswimmers. Throughout, I emphasize open problems in which fluid dynamical methods are key ingredients in an interdisciplinary approach to the mysteries of life.

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“…to determine the coherent collective dynamics of charge-density waves in TbTe 3 and K 0.3 MoO 3 [5,6]. In the nickelates, equilibrium investigations have revealed a pseudogap phenomenology, exposed in the optical response as a strong suppression of the mid-infrared conductivity followed by the formation of an energy gap below the stripe-ordering transition [7][8][9]. These features yield an optical probe of low-energy charge correlations in the nickelates.…”

Section: Introductionmentioning

confidence: 99%