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Lookup NU author(s): Dr Andrew Baggaley
This is the final published version of an article that has been published in its final definitive form by American Physical Society, 2018.
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We study the effects of imposed three-dimensional flows on the trajectories and mixing of gyrotactic swimming microorganisms and identify phenomena not seen in flows restricted to two dimensions. Through numerical simulation of Taylor-Green and Arnold-Beltrami- Childress (ABC) flows, we explore the role that the flow and the cell shape play in determining the long-term configuration of the cells’ trajectories, which often take the form of multiple sinuous and helical “plumelike” structures, even in the chaotic ABC flow. This gyrotactic suppression of Lagrangian chaos persists even in the presence of random noise. Analytical solutions for a number of cases reveal the how plumes form and the nature of the competition between torques acting on individual cells. Furthermore, studies of Lyapunov exponents reveal that, as the ratio of cell swimming speed relative to the flowspeed increases from zero, the initial chaotic trajectories are first suppressed and then give way to a second unexpected window of chaotic trajectories at speeds greater than unity, before suppression of chaos at high relative swimming speeds.
Author(s): Heath-Richardson SI, Baggaley AW, Hill NA
Publication type: Article
Publication status: Published
Journal: Physical Review Fluids
Print publication date: 23/02/2018
Online publication date: 23/02/2018
Acceptance date: 15/01/2018
Date deposited: 26/02/2018
ISSN (electronic): 2469-990X
Publisher: American Physical Society
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