Hydrodynamic fluctuations and instabilities in ordered suspensions of self-propelled particles.

By R. Aditi Simha, S. Ramaswamy. Physical Review Letters, 2001

766 citations recorded by the source corpus.

We construct the hydrodynamic equations for suspensions of self-propelled particles (SPPs) with spontaneous orientational order, and make a number of striking, testable predictions: (i) Nematic SPP suspensions are always absolutely unstable at long wavelengths. (ii) SPP suspensions support novel propagating modes at long wavelengths, coupling orientation, flow, and concentration. (iii) In a wave number regime accessible only in low Reynolds number systems such as bacteria, polar-ordered suspensions are invariably convectively unstable. (iv) The variance in the number N of particles, divided by the mean , diverges as (2/3 ) in polar-ordered SPP suspensions.

Subfields: Condensed Matter Physics, Mechanical Engineering, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/087d6c0b11198a307ac7f25d85ba2e9e6619d387

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Citations in the corpus

Meso-scale turbulence in living fluids (2012, methodology): “[19] presents an active stress contribution (in mean-field approximation) as known from theories of active nematics [15].”
Topological active matter (2020, background): “Bulk active nematics are susceptible to a generic hydrodynamic instability [58] that spontaneously generates individual disclination loops [103–105].”
Spherical squirmers: models for swimming micro-organisms (2016, background): “Non-gravitational instabilities have also been discovered in suspensions of bacteria (though not algae), driven by the stresses applied to the fluid by the swimmers themselves (Simha & Ramaswamy, 2002; Saintillan & Shelley, 2008; Ezhilan et al., 2013).”
Tuned, driven, and active soft matter (2015, background): “located asymmetrically with respect to the centers of force acting on the surrounding fluid, it will experience a drag from the self-induced fluid flow [517, 524, 525].”
Bacterial ratchet motors (2009, background): “Suspensions of self propelling bacteria can be viewed as a class of strongly non-equilibrium fluids, often referred to as active matter [7, 8, 9, 10, 11].”
Fluid flows created by swimming bacteria drive self-organization in confined suspensions (2014, background): “[17] Simha RA, Ramaswamy S (2002) Hydrodynamic Fluctuations and Instabilities in Ordered Suspensions of Self-”
Minimal model of active colloids highlights the role of mechanical interactions in controlling the emergent behavior of active matter (2015, background): “The q−2 divergence of the structure factor as q → 0 is also the signature of the giant number fluctuations (GNF) predicted and observed ubiquitously in the ordered state of flocking models [48, 49, 50, 3].”