Hydrodynamic Fluctuations and Instabilities in Ordered Suspensions of Self-Propelled Particles

2001/08/31 by Robert Simha, R. Aditi Simha, Sriram Ramaswamy +1 · 43 citations
Biochemistry, Genetics and Molecular Biology · Engineering · Physics and Astronomy · #Diffusion and Search Dynamics #Micro and Nano Robotics #Modular Robots and Swarm Intelligence #cond-mat.soft #cond-mat.stat-mech #q-bio.QM

paper · pdf · doi:10.1103/physrevlett.89.058101

submitted to Phys Rev Lett

arxiv created 2002/03/19 · openalex publication_date 2002/07/15 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

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 <N>, diverges as <N >(2/3 ) in polar-ordered SPP suspensions.

Citations

• The Physics of Liquid Crystals
• Unified Hydrodynamic Theory for Crystals, Liquid Crystals, and Normal Fluids

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