Viscosity of bacterial suspensions : hydrodynamic interactions and self-induced noise.

Journal Article · Sun May 01 04:00:00 EDT 2011 · Phys. Rev. Lett.

DOI:https://doi.org/10.1103/PhysRevE.83.050904· OSTI ID:1015944

Ryan, S D; Haines, B M; Berlyand, L V; Ziebert, F; Aranson, I S ^[1]

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1. Materials Science Division

The viscosity of a suspension of swimming bacteria is investigated analytically and numerically. We propose a simple model that allows for efficient computation for a large number of bacteria. Our calculations show that long-range hydrodynamic interactions, intrinsic to self-locomoting objects in a viscous fluid, result in a dramatic reduction of the effective viscosity. In agreement with experiments on suspensions of Bacillus subtilis, we show that the viscosity reduction is related to the onset of large-scale collective motion due to interactions between the swimmers. The simulations reveal that the viscosity reduction occurs only for relatively low concentrations of swimmers: Further increases of the concentration yield an increase of the viscosity. We derive an explicit asymptotic formula for the effective viscosity in terms of known physical parameters and show that hydrodynamic interactions are manifested as self-induced noise in the absence of any explicit stochasticity in the system.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1015944
• Report Number(s): ANL/MSD/JA-68791
• Journal Information: Phys. Rev. Lett., Journal Name: Phys. Rev. Lett. Journal Issue: May 2011 Vol. 83; ISSN 1539-3755
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
ASYMPTOTIC SOLUTIONS
BACILLUS SUBTILIS
BACTERIA
FLUIDS
HYDRODYNAMICS
MOTION
SIMULATION
VISCOSITY