Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session D23: Biological Fluid Dynamics: Locomotion - Active Suspensions
2:30 PM–4:14 PM,
Sunday, November 18, 2018
Georgia World Congress Center
Room: B311
Chair: Sebastian Fürthauer, Simons Foundation
Abstract ID: BAPS.2018.DFD.D23.5
Abstract: D23.00005 : Mixing & transport of microorganisms in 2D time-periodic flows*
3:22 PM–3:35 PM
Presenter:
Brendan C Blackwell
(University of Pennsylvania)
Authors:
Brendan C Blackwell
(University of Pennsylvania)
Boyang Qin
(Princeton)
Paulo E. Arratia
(Univ of Pennsylvania)
In this talk, we examine the effect of swimming bacteria on transport, diffusion, and mixing in time-periodic flows. An oscillatory two-dimensional flow is generated by driving a sinusoidal current through a conducting fluid (salt water) that is situated atop an array of magnets. We perform experiments with an ordered lattice to create regular vortices and with a random configuration to create a spatially disordered flow pattern; the Reynolds number ranges from 0.1 to 100. Two types of fluids are used: (1) a simple Newtonian liquid (water) and (2) a mixture of water and bacteria (Vibrio cholerae). Velocimetry data are used to calculate the flow stretching fields and Lyapunov exponents. Results with plain salt water are compared to results with the addition of varying concentrations of V. cholerae. We find that the addition of active bacteria, even in dilute quantities, results in significant changes to the stretching fields even though the Eulerian velocity fields remain quite similar. We also perform experiments with fluorescent dye, both with and without bacteria, to more directly characterize mixing. These data also show a substantial difference between the active suspension and the control case, even with small concentrations of bacteria.
*This work supported by NSF-DMR-1709763
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.DFD.D23.5
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