Viscous pumping inspired by flexible propulsion

Arco, Roger M.; Vélez-Cordero, J. Rodrigo; Lauga, Eric; Zenit, Roberto

doi:10.1088/1748-3182/9/3/036007

Cited by 12 publications

(10 citation statements)

References 35 publications

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“…Robotics approaches at the macroscale have long been used successfully to explore and validate fluid dynamical theories of self-propulsion [47,48]. Scenarios can be tested in robots that may not be possible in the live organism [49,50]. Dynamically-scaled robotic models of microswimmers operating in viscous media have been used to mimic bacterial swimming [51], to examine flows induced by bundles of rotating flagella [52], and to reveal the role of elasticity [53], or to investigate metachronal actuation of rigid appendages [54].…”

Section: Discussionmentioning

confidence: 99%

A minimal robophysical model of quadriflagellate self-propulsion

Diaz

Robinson

Ozkan-Aydin

et al. 2021

Preprint

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Locomotion at the microscale is remarkably sophisticated. Microorganisms have evolved diverse strategies to move within highly viscous environments, using deformable, propulsion-generating appendages such as cilia and flagella to drive helical or undulatory motion. In single-celled algae, these appendages can be arranged in different ways around an approximately 10μm cell body, and coordinated in distinct temporal patterns. Inspired by the observation that some quadriflagellates (bearing four flagella) have an outwardly similar morphology and flagellar beat pattern, yet swim at different speeds, this study seeks to determine whether variations in swimming performance could arise solely from differences in swimming gait. Robotics approaches are particularly suited to such investigations, where the phase relationships between appendages can be readily manipulated. Here, we developed autonomous, algae-inspired robophysical models that can self-propel in a viscous fluid. These macroscopic robots (length and width = 8.5 cm, height = 2 cm) have four independently actuated `flagella' that oscillate back and forth under low-Reynolds number conditions (Re=0.1-0.5). We tested the swimming performance of these robot models with appendages arranged in one of two distinct configurations, and coordinated in one of three distinct gaits. The gaits, namely the pronk, the trot, and the gallop, correspond to gaits adopted by distinct microalgal species. When the appendages are inserted perpendicularly around a central `body', the robot achieved a net performance of 0.15-0.63 body lengths per cycle, with the trot gait being the fastest. Robotic swimming performance was found to be comparable to that of the algal microswimmers across all gaits, with parallel appendage placement consistently leading to slower propulsion. By creating a minimal robot that can successfully reproduce cilia-inspired drag-based swimmging, our work paves the way for the design of next-generation devices that have the capacity to autonomously navigate aqueous environments.

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Section: Discussionmentioning

confidence: 99%

A minimal robophysical model of quadriflagellate self-propulsion

Diaz

Robinson

Ozkan-Aydin

et al. 2021

Preprint

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“…A rotating helical slender body, a typical model micro-swimmer propelling like a cork-screw, attains the most efficient propulsion when the relaxation time of the polymeric fluid it is immersed in is of the order of the typical flow time 61,62 . Similarly, an elastic filament 63,64 or flapper 65 actuated in a viscous fluid for propulsion or pumping reaches maximum efficiency as the so-called sperm number 66 , the ratio of the time scale of the elastic structure over that of the flow, is of order one. We further note that the relation between the optimal capillary number and the frequency of the applied shear could be potentially used to aid the design of flow-assisted devices to sort deformable cells [67][68][69] .…”

Section: A Trajectoriesmentioning

confidence: 99%

The dynamics of a capsule in a wall-bounded oscillating shear flow

2015

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The motion of an initially spherical capsule in a wall-bounded oscillating shear flow is investigated via an accelerated boundary integral implementation. The neo-Hookean model is used as the constitutive law of the capsule membrane. The maximum wall-normal migration is observed when the oscillation period of the imposed shear is of the order of the relaxation time of the elastic membrane; hence, the optimal capillary number scales with the inverse of the oscillation frequency and the ratio agrees well with the theoretical prediction in the limit of high-frequency oscillation.The migration velocity decreases monotonically with the frequency of the applied shear and the capsule-wall distance. We report a significant correlation between the capsule lateral migration and the normal stress difference induced in the flow.The periodic variation of the capsule deformation is roughly in phase with that of the migration velocity and normal stress difference, with twice the frequency of the imposed shear. The maximum deformation increases linearly with the membrane elasticity before reaching a plateau at higher capillary numbers when the deformation is limited by the time over which shear is applied in the same direction and not by the membrane deformability. The maximum membrane deformation scales as the distance to the wall to the power 1/3 as observed for capsules and droplets in nearwall steady shear flows.

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“…The experimental data showed good agreement with both linear and nonlinear theoretical predictions. Other relevant works include Camalet and Jülicher [5], who studied the dynamics of an elastic filament actuated by internal moments, and Arco et al [6], who experimentally studied oscillating flexible sheet as a novel pumping mechanism in the creeping flow regime.…”

Section: Introductionmentioning

confidence: 99%

Propulsion and maneuvering of an artificial microswimmer by two closely spaced waving elastic filaments

2018

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This work examines the effect of hydrodynamic interaction between two closely spaced waving elastic filaments on the propulsion and maneuvering of an artificial microswimmer. The filaments are actuated by a forced oscillation of the slope at their clamped end and are free at the opposite end. We obtain an expression for the interaction force and apply an asymptotic expansion based on a small parameter representing the ratio between the elastic deflections and the distance between the filaments. The leading-order interaction forces yield asymmetric oscillation patterns at the two frequencies (ω 1 ,ω 2) in which the filaments are actuated. Higher orders oscillate at frequencies which are combinations of the actuation frequencies, where the first order includes the 2ω 1 , 2ω 2 , ω 1 + ω 2 , and ω 1 − ω 2 harmonics. For configurations with ω 1 ≈ ω 2 , the ω 1 − ω 2 mode represents the dominant first-order interaction effect due to significantly smaller effective Sperm number. For in-phase actuation with ω 1 = ω 2 , the deflection dynamics are identical to an isolated filament with a modified Sperm number. Phase difference between the filaments is shown to have significant effect on the time-averaged forces. Optimal Sperm numbers for in-phase and antiphase actuation are calculated. Turning moments due to phase difference between the filaments are presented, yielding optimal maneuvering for phase of 90 •. Calculation of the effect of hydrodynamic interaction on the propulsive forces yielded that antiphase beating is more efficient than the in-phase scenario, in contrast with the commonly used assumption of maximal efficiency of the synchronized state. Experiments are conducted to verify and illustrate some of the theoretical predictions.

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Viscous pumping inspired by flexible propulsion

Cited by 12 publications

References 35 publications

A minimal robophysical model of quadriflagellate self-propulsion

A minimal robophysical model of quadriflagellate self-propulsion

The dynamics of a capsule in a wall-bounded oscillating shear flow

Propulsion and maneuvering of an artificial microswimmer by two closely spaced waving elastic filaments

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