Experimental study of the deflections of curved plates exposed to pulsating cross-flows

Vicente, W.; Hernández-Badillo, C.; Zenit, Roberto

doi:10.1007/s00707-016-1687-1

Cited by 2 publications

(2 citation statements)

References 25 publications

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“…2). In plants, such chordwise geometry enables different compliances under bending with opposite orientations, with the structure bending toward the concave face (Guzmán et al, 2016;Wei et al, 2022), analogous to the recovery stroke in P. vulgaris. This mechanism is reminiscent of construction site measuring tapes whose chordwise curvature -which coincidentally have similar values to P. vulgaris -gives them strength when measuring with the concave surface facing upward and resisting gravity but high flexibility for winding in the casing.…”

Section: The Role Of Pleopod Passive Bendingmentioning

confidence: 99%

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Going around the bend to understand the role of leg coalescence in metachronal swimming

Tack,

Santos,

Wilhelmus

2024

Preprint

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Many of the most abundant aquatic invertebrates display metachronal swimming by sequentially beating closely spaced flexible appendages. Common biophysical mechanisms like appendage spatial asymmetry and phase drive the success and performance of this locomotor mode, which is generally explained by the need to maximize thrust production. However, the potential role of these mechanisms in drag reduction, another important contributor to the overall swimming performance, has yet to be evaluated. We present a comprehensive overview of the morphological, functional, and physical mechanisms promoting drag reduction during metachronal swimming by exploring appendage differential bending and leg grouping (coalescence). We performed μ-CT and in-vivo velocimetry measurements of shrimp (Palaemonetes vulgaris) to design a five-legged robotic metachronal analog. This test platform enabled simultaneous flow and force measurements to quantify the thrust and drag forces produced by flexible and stiff pleopods (legs) beating independently or coalescing. We tested the hypothesis that coalescence and bending effectively reduce drag during the recovery stroke (RS). The curved cross-section of the pleopods enables passive asymmetrical bending during the RS to reduce their coefficient of drag by up to 75.8% relative to stiff pleopods. Bending promotes physical interactions facilitating the coalescence of three pleopods at any time during the RS to reduce drag such that the mean net thrust produced during coalescence is increased by 30.2%. These improvements are explained by the production of a weaker wake compared with stiff and non-coalescing pleopods. Our results describe fundamental biological and physical components of metachronal propulsion that may aid the development of novel bio-inspired underwater vehicles.

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Section: The Role Of Pleopod Passive Bendingmentioning

confidence: 99%

Section: The Role Of Pleopod Passive Bendingmentioning

confidence: 99%

Going around the bend to understand the role of leg coalescence in metachronal swimming

Tack,

Santos,

Wilhelmus

2024

Preprint

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Flexible structures enhance fluid mixing in a channel flow

Singh,

Senapati,

Sharma

et al. 2024

Physics of Fluids

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Early fluid mixing in channel flows without incurring much drop in the pressure head is desired in industrial applications. This study explores wall-mounted flexible plates as obstacles to enhance mixing in channel flows. Using fluid–structure-scalar interaction simulations, we investigate the oscillations of the flexible plates under the flow, which serve as a vortex generator and help increase the mixing. The channel flow involves a scalar field with distinct concentrations initially separated across the channel, gradually intermixing due to vortical structures of varying scales. We have used the “mixing index” and “head loss” metrics along the channel length to assess the mixing quality when plates with different flexibility (characterized by the Cauchy number, Ca) are used. This study introduces a comprehensive criterion, the “coefficient of performance,” derived by comparing mixing and head loss in the presence and absence of obstacles. Aggregating results across various Ca values reveal that flexible plates substantially improve fluid mixing compared to rigid plates. We have also investigated the effect of the pulsatile fluid inlet (quantified by Strouhal number, Stf) and found that lower inlet flow pulsation (Stf<32) adversely impacts mixing performance, recommending a steady inlet flow. However, at high Stf, specifically in the configuration with Ca = 0.06 and Stf = 32, the best mixing performance is achieved in the channel, which marginally outperforms the steady inlet case. The conclusive takeaways from this study are that the plates with increased flexibility result in better mixing, and high inlet pulsation can be employed to fine-tune the mixing performance for further enhancement.

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Experimental study of the deflections of curved plates exposed to pulsating cross-flows

Cited by 2 publications

References 25 publications

Going around the bend to understand the role of leg coalescence in metachronal swimming

Going around the bend to understand the role of leg coalescence in metachronal swimming

Flexible structures enhance fluid mixing in a channel flow

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