Dynamics of a hydrofoil free to oscillate in the wake of a fixed, constantly rotating or periodically rotating cylinder

Currier, Todd; Carleton, Adrian; Modarres‐Sadeghi, Yahya

doi:10.1017/jfm.2021.539

Cited by 5 publications

(4 citation statements)

References 40 publications

(52 reference statements)

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“…To visualize the flow, we used bubble image velocimetry (BIV) following the steps that we discussed in our previous work [8]. The major change in flow visualisation in the present work was that the 0.002-in-diameter platinum-iridium wire was taut upstream vertically (instead of horizontally) to enable a visualisation of the vortices from the side.…”

Section: Experimental Setup and Methodsmentioning

confidence: 99%

“…In our previous work [8] we had shown that the frequency of the cylinder's rotation plays an important role in the observed response of the hydrofoil downstream, since the shedding frequency is controlled by the rotation frequency. We had shown that when the cylinder is forced to rotate periodically with a constant 1:1 ratio between CW and CCW rotations, then both figure-eight and linear trajectories are observed in the hydrofoil's response.…”

Section: The Experimentsmentioning

confidence: 99%

“…Previously, we had investigated the response of a minimally constrained hydrofoil (i.e. one hung from a string and otherwise free to move) placed in the wake of a cylinder [8]. In that work, we had considered the response of the hydrofoil when the cylinder was (i) fixed, (ii) forced to rotate in one direction, or (iii) forced to rotate periodically.…”

Section: Introductionmentioning

confidence: 99%

“…In our previous work [8], we investigated how a hydrofoil placed in the wake of such a cylinder reacts to the changes in the shedding patterns of the cylinder. We showed that when the cylinder is fixed, the hydrofoil interacts with the vortices that are shed in the cylinder's wake and oscillates at a frequency equal to the shedding frequency.…”

Section: Introductionmentioning

confidence: 99%

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Passive double pendulum in the wake of a cylinder forced to rotate emulates a cyclic human walking gait

Carleton¹,

Sup²,

Modarres‐Sadeghi³

2022

Bioinspir. Biomim.

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The goal of this work is to present a method based on fluid-structure interactions to enforce a desired trajectory on a passive double pendulum. In our experiments, the passive double pendulum represents human thigh and shank segments, and the interaction between the fluid and the structure comes from a hydrofoil attached to the double pendulum and interacting with the vortices that are shed from a cylinder placed upstream. When a cylinder is placed in flow, vortices are shed in the wake of the cylinder. When the cylinder is forced to rotate periodically, the frequency of the vortices that are shed in its wake can be controlled by controlling the frequency of cylinder's rotation. These vortices exert periodic forces on any structure placed in the wake of this cylinder. In our system, we placed a double pendulum fitted with a hydrofoil at its distal end in the wake of a rotating cylinder. The vortices exerted periodic forces on this hydrofoil which then forced the double pendulum to oscillate. We controlled the cylinder to rotate periodically, and measured the displacement of the double pendulum. By comparing the joint positions of the double pendulum with those of human hip, knee and ankle joint positions during walking, we show how the system is able to generate a human walking gait cycle on the double pendulum only using the interactions between the vortices and the hydrofoil.

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Section: Experimental Setup and Methodsmentioning

confidence: 99%

Section: The Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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