Swimming sheet near a plane surfactant-laden interface

Shaik, Vaseem A.; Ardekani, Arezoo M.

doi:10.1103/physreve.99.033101

Cited by 10 publications

(6 citation statements)

References 59 publications

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“…Near a viscous drop, the surfactant increases the trapping capability [120] and can even break the kinematic reversibility associated with the inertialess realm of swimming microorganisms [123]. In contrast to that, the presence of a surfactant near a planar interface was found not to change the reorientation dynamics [74] but to change the swimming speed [124] in addition to the circling direction [74].…”

Section: Introductionmentioning

confidence: 87%

Towards an analytical description of active microswimmers in clean and in surfactant-covered drops

et al. 2020

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Abstract. Geometric confinements are frequently encountered in the biological world and strongly affect the stability, topology, and transport properties of active suspensions in viscous flow. Based on a far-field analytical model, the low-Reynolds-number locomotion of a self-propelled microswimmer moving inside a clean viscous drop or a drop covered with a homogeneously distributed surfactant, is theoretically examined. The interfacial viscous stresses induced by the surfactant are described by the well-established Boussinesq-Scriven constitutive rheological model. Moreover, the active agent is represented by a force dipole and the resulting fluid-mediated hydrodynamic couplings between the swimmer and the confining drop are investigated. We find that the presence of the surfactant significantly alters the dynamics of the encapsulated swimmer by enhancing its reorientation. Exact solutions for the velocity images for the Stokeslet and dipolar flow singularities inside the drop are introduced and expressed in terms of infinite series of harmonic components. Our results offer useful insights into guiding principles for the control of confined active matter systems and support the objective of utilizing synthetic microswimmers to drive drops for targeted drug delivery applications. Graphical abstract

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Section: Introductionmentioning

confidence: 87%

Towards an analytical description of active microswimmers in clean and in surfactant-covered drops

et al. 2020

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“…Additionally, we characterize the flow within the thin film of liquid directly in contact with the undulator by performing 2D particle image velocimetry (PIV) measurements. Our experimental design is essentially a mesoscale realization of the Taylor's sheet 30 placed near a free surface 31,32 ; the crucial difference, however, is that the sheet or undulator is held stationary here, in contrast to free swimming.…”

Section: Methodsmentioning

confidence: 99%

Optimal free-surface pumping by an undulating carpet

Pandey,

Chen,

Yuk

et al. 2023

Nat Commun

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Examples of fluid flows driven by undulating boundaries are found in nature across many different length scales. Even though different driving mechanisms have evolved in distinct environments, they perform essentially the same function: directional transport of liquid. Nature-inspired strategies have been adopted in engineered devices to manipulate and direct flow. Here, we demonstrate how an undulating boundary generates large-scale pumping of a thin liquid near the liquid-air interface. Two dimensional traveling waves on the undulator, a canonical strategy to transport fluid at low Reynolds numbers, surprisingly lead to flow rates that depend non-monotonically on the wave speed. Through an asymptotic analysis of the thin-film equations that account for gravity and surface tension, we predict the observed optimal speed that maximizes pumping. Our findings reveal how proximity to free surfaces, which ensure lower energy dissipation, can be leveraged to achieve directional transport of liquids.

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“…The tangential flows and resultant swimmer dynamics generally depend on the relative obstacle size or interfacial confinement and the common possibility that surfactants are present on the interface (Figure 9d) (159,169). Surfactants can rigidify the interface and nudge the system back towards Type III interactions of a swimmer with a rigid obstacle or wall (170,171).…”

Section: Geometric Obstaclesmentioning

confidence: 99%

Swimming in Complex Fluids

Spagnolie¹,

Underhill²

2022

Preprint

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We review the literature on swimming in complex fluids. A classification is proposed by comparing the length and time scales of a swimmer with those of nearby obstacles, interpreted broadly, extending from rigid or soft confining boundaries to molecules which confer the bulk fluid with complex stresses. A third dimension in the classification is the concentration of swimmers, which incorporates fluids whose complexity arises purely by the collective motion of swimming organisms. For each of the eight system classes which we identify we provide a background and describe modern research findings. While some classes have seen a great deal of attention for decades, others remain uncharted waters still open and awaiting exploration.

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Swimming sheet near a plane surfactant-laden interface

Cited by 10 publications

References 59 publications

Towards an analytical description of active microswimmers in clean and in surfactant-covered drops

Towards an analytical description of active microswimmers in clean and in surfactant-covered drops

Optimal free-surface pumping by an undulating carpet

Swimming in Complex Fluids

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