Helicoidal particles and swimmers in a flow at low Reynolds number

Ishimoto, Kenta

doi:10.1017/jfm.2020.142

Cited by 17 publications

(30 citation statements)

References 53 publications

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“…The same result has been rederived recently in (40). To model tumbling, we include tumble events that modify the bacterium orientation instantaneously at exponentially distributed times (see Materials and Methods).…”

Section: Theoretical Frameworkmentioning

confidence: 70%

Chirality-induced bacterial rheotaxis in bulk shear flows

et al. 2020

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Interaction of swimming bacteria with flows controls their ability to explore complex environments, crucial to many societal and environmental challenges and relevant for microfluidic applications such as cell sorting. Combining experimental, numerical, and theoretical analysis, we present a comprehensive study of the transport of motile bacteria in shear flows. Experimentally, we obtain with high accuracy and, for a large range of flow rates, the spatially resolved velocity and orientation distributions. They are in excellent agreement with the simulations of a kinematic model accounting for stochastic and microhydrodynamic properties and, in particular, the flagella chirality. Theoretical analysis reveals the scaling laws behind the average rheotactic velocity at moderate shear rates using a chirality parameter and explains the reorientation dynamics leading to saturation at large shear rates from the marginal stability of a fixed point. Our findings constitute a full understanding of the physical mechanisms and relevant parameters of bacteria bulk rheotaxis.

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Section: Theoretical Frameworkmentioning

confidence: 70%

Chirality-induced bacterial rheotaxis in bulk shear flows

et al. 2020

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“…These results clearly indicated that cell motility was essential for the migration and rheotaxis. The results may also be derived mathematically under Stokes flow conditions, given that drift and alignment do not appear for a body shape with plane symmetry (Kim & Karrila 1992;Ishimoto 2020).…”

Section: Simulation Resultsmentioning

confidence: 99%

Rheotaxis and migration of an unsteady microswimmer

et al. 2021

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Rheotaxis and migration of cells in a flow field have been investigated intensively owing to their importance in biology, physiology and engineering. In this study, first, we report our experiments showing that the microalgae Chlamydomonas can orient against the channel flow and migrate to the channel centre. Second, by performing boundary element simulations, we demonstrate that the mechanism of the observed rheotaxis and migration has a physical origin. Last, using a simple analytical model, we reveal the novel physical mechanisms of rheotaxis and migration, specifically the interplay between cyclic body deformation and cyclic swimming velocity in the channel flow. The discovered mechanism can be as important as phototaxis and gravitaxis, and likely plays a role in the movement of other natural microswimmers and artificial microrobots with non-reciprocal body deformation.

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“…For |B| < 1, the dynamics of Eq. ( 16) are precisely those of the classic Jeffery's orbits, with periodic rotation occurring ad infinitum; for |B| > 1, the solution approaches one of two stable steady states, as discussed by Bretherton [33] and more recently by Ishimoto [35]. This latter work, and its recent generalisation [36], further extended the Jeffery's orbit description to bodies with particular symmetries, far removed from the original ellipsoidal considerations of Jeffery.…”

Section: Yawing In Shear Flowmentioning

confidence: 80%

“…Ellipsoid models in particular afford the significant advantage of having been the subject of much classical and recent study, with their behaviour in shear flow being the topic of Jeffery's seminal work of 1922 [32]. Since then, Jeffery's analytical results, which we partially recount in Section III, have been extended and generalised [33][34][35][36]. In particular, the work of Bretherton [33] and the recent contribution of Ishimoto [36] considered broader classes of rigid bodies, including surfaces of revolution and those with particular symmetries.…”

Section: Introductionmentioning

confidence: 99%

The effects of rapid yawing on simple swimmer models and planar Jeffery's orbits

Walker,

Ishimoto,

Gaffney

et al. 2021

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Over a sufficiently long period of time, or from an appropriate distance, the motion of many swimmers can appear smooth, with their trajectories appearing almost ballistic in nature and slowly varying in character. These long-time behaviours, however, often mask more complex dynamics, such as the side-to-side snakelike motion exhibited by spermatozoa as they swim, propelled by the frequent and periodic beating of their flagellum. Many models of motion neglect these effects in favour of smoother long-term behaviours, which are often of greater practical interest than the small-scale oscillatory motion. Whilst it may be tempting to ignore any yawing motion, simply assuming that any effects of rapid oscillations cancel out over a period, a precise quantification of the impacts of high-frequency yawing is lacking. In this study, we systematically evaluate the longterm effects of general high-frequency oscillations on translational and angular motion, cast in the context of microswimmers but applicable more generally. Via a multiple-scales asymptotic analysis, we show that rapid oscillations can cause a long-term bias in the average direction of progression. We identify sufficient conditions for an unbiased long-term effect of yawing, and we quantify how yawing modifies the speed of propulsion and the effective hydrodynamic shape when in shear flow. Furthermore, we investigate and justify the long-time validity of the derived leading-order solutions and, by direct computational simulation, we evidence the relevance of the presented results to a canonical microswimmer.

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Helicoidal particles and swimmers in a flow at low Reynolds number

Cited by 17 publications

References 53 publications

Chirality-induced bacterial rheotaxis in bulk shear flows

Chirality-induced bacterial rheotaxis in bulk shear flows

Rheotaxis and migration of an unsteady microswimmer

The effects of rapid yawing on simple swimmer models and planar Jeffery's orbits

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