Scaling laws for drag-to-thrust transition and propulsive performance in pitching flexible plates

Peng, Ze-Rui; Sun, Yuehao; Yang, Dan; Xiong, Yongliang; Wang, Lei; Wang, Lin

doi:10.1017/jfm.2022.268

Cited by 8 publications

(18 citation statements)

References 35 publications

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“…When driving at resonance condition, our model fails to give the accurate response parameter as that from simulation provided by Peng et al (2022). This is because the driving pitching amplitude used by Peng et al is 0.1, which makes the finalized pitching amplitude obviously larger than the ones that the linear inviscid theory holds.…”

Section: Model Validationmentioning

confidence: 72%

Analytical results for pitching kinematics and propulsion performance of flexible foil

Du,

2024

J. Fluid Mech.

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Natural flyers and swimmers employ flexible wings or fins to propel. While the complex interaction between the foil with deformation and the surrounding non-steady fluid environment defines the propulsion performance of the propellers, elucidating the interaction mechanism through theoretical models earns much challenge. Based on elastokinetics and linear potential flow theory, this study proposes a simplified analytical model to clarify the kinematics and the propulsion performance of a flexible thin foil pitching in flow. The dynamical forces, including the inertial force of the foil and the non-steady fluid pressure, are used to determine the averaged deformation angle of the foil. Combining the averaged deformation angle and the prescribed driving pitching motion, the kinematics of the foil is resolved analytically. Based on the analytical expressions for the corresponding pitching motion, analytical relations among the physical parameters of the stiffness and the mass of the foil and the driving frequency are given to these critical conditions, including resonance of the flow–structure system, equal pitching amplitude between the flexible foil and the rigid counterpart, phase angle transition from ${\rm \pi}/2$ to $- {\rm \pi}/2$ . Subsequently, the performance of the foil, including the thrust, the power and the propulsive efficiency, as a function of the flexibility of the foil are derived, together with the introduction of a bluff body type offset drag to the thrust. The formulated analytical theory, which matches nicely with previous reports, will help to interpret the effect of the flexibility and regulate the propulsive performance of the flexible foil when pitching in fluid.

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Section: Model Validationmentioning

confidence: 72%

Analytical results for pitching kinematics and propulsion performance of flexible foil

Du,

2024

J. Fluid Mech.

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“…Peng et al. (2022) have shown that, for a passive pitching foil, while the trailing-edge kinematics is a valid representative for the propulsion performance (e.g. power coefficient), using the entire motion of the foil slightly better represents the propulsion performance.…”

Section: Resultsmentioning

confidence: 99%

“…The resonance theory proposes that fish adjust the structural stiffness to match the resonance frequency of the system with the beating frequency, thereby reducing energy consumption (Blight 1977). The theory is supported by several experimental and computational studies, which found that the local thrust peaks of a plunging plate coincide with its trailing-edge amplitude peaks in the beating frequency spectrum and the efficiency peaks also largely correspond to the thrust peaks (Quinn, Lauder & Smits 2014;Floryan & Rowley 2018;Hoover et al 2018;Peng et al 2022). Some other studies which support the hydrodynamics mechanism, however, did not observe the match of the frequencies.…”

Section: Introductionmentioning

confidence: 92%

“…In both studies, the trailing-edge motion is passive, following the motion of the leading edge, and it aims to minimize the flow pressure difference on the fin. Peng et al (2022) have shown that, for a passive pitching foil, while the trailing-edge kinematics is a valid representative for the propulsion performance (e.g. power coefficient), using the entire motion of the foil slightly better represents the propulsion performance.…”

Section: Effective Angle Of Attackmentioning

confidence: 99%

“…2018; Peng et al. 2022). Some other studies which support the hydrodynamics mechanism, however, did not observe the match of the frequencies.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of antagonistic muscle actuation on the bilaminar structure of ray-finned fish in propulsion

Bodaghi,

Wang,

Xue

et al. 2023

J. Fluid Mech.

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In this study, the effects of antagonistic muscle actuation on the propulsion of a bilaminar-structure fish fin ray were investigated using a two-dimensional computational flow–structure interaction (FSI) model. The structure and material properties of the model were based on the realistic biological data of the sunfish fin. The effect of muscle actuation was modelled using root displacement offset between the two hemitrichs. Parametric FSI simulations were conducted by assuming a sinusoidal function of the offset over a cycle and varying the amplitude and phase difference between the actuations and pitching/plunging motions. The results show that the phase of muscle actuation is a critical factor affecting its effects. Three performance regions can be identified with different phase ranges, including a thrust-favour region, an efficiency-favour region and a thrust-efficiency-unfavour region. In each region, the relationships among the root actuations, fin-ray kinematics, vortex dynamics and resulting performance are studied and discussed. Furthermore, a strong positive correlation between the trailing–leading amplitude ratio and thrust coefficient as well as a negative relationship between the efficiency and angle of attack at the centre of mass of the fin ray are observed.

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Force and torque reactions on a pitching flexible aerofoil

2023

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Experimental measurements in a wind tunnel of the unsteady force and moment that a fluid exerts on flexible flapping aerofoils are not trivial because the forces and moments caused by the aerofoil's inertia and others structural tensions at the pivot axis have to be obtained separately and subtracted from the direct measurements with a force/torque sensor. Here we derive from the nonlinear beam equation general relations for the force and torque reactions at the leading edge of a pitching aerofoil in terms of the fluid force and moment on the aerofoil and its kinematics, involving geometric and structural parameters of the flexible aerofoil. These relations are validated by comparing high-resolution numerical simulations of the flow–structure interaction of a two-dimensional flexible aerofoil pitching about its leading edge with direct force and torque measurements in a wind tunnel.

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Scaling laws for drag-to-thrust transition and propulsive performance in pitching flexible plates

Cited by 8 publications

References 35 publications

Analytical results for pitching kinematics and propulsion performance of flexible foil

Analytical results for pitching kinematics and propulsion performance of flexible foil

Effects of antagonistic muscle actuation on the bilaminar structure of ray-finned fish in propulsion

Force and torque reactions on a pitching flexible aerofoil

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