The effect of wing flexibility on sound generation of flapping wings

Geng, Biao; Xue, Qian; Zheng, Xudong; Li, Geng; Ren, Yan; Dong, Haibo

doi:10.1088/1748-3190/aa8447

Cited by 42 publications

(45 citation statements)

References 27 publications

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“…We believe that the application of this method to the current case of flapping wing flight is appropriate because it falls under the category of low-Mach flows and the Reynolds number is comparable to the validated cases. Our previous study [20] also showed that the directivity of the computed sound from the flapping wings was comparable to experimental measurements [17].…”

Section: ∇•supporting

confidence: 72%

“…Previous experimental [17] and simulation works [18,19] on the sound production of flapping wings generally found that the flapping tone is directional and changes with flight conditions. Geng et al [20] showed that the flapping tone is mainly generated by the fluctuating aerodynamic forces. The sound signal and the force signal were related in both radiation pattern and amplitude.…”

Section: Introductionmentioning

confidence: 99%

“…Aside from the quantitative changes in aerodynamic forces and power requirements, flexibility is deemed to not affect the fundamental force production mechanism [1]. Geng et al [20] showed that wing flexibility changes the directivity of the flapping tone and helps reduce the sound pressure level through reduced aerodynamic forces. However, the study is limited to only two cases, one using reconstructed cicada wing kinematics and the other using simple flapping kinematics.…”

Section: Introductionmentioning

confidence: 99%

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A Numerical Study of the Sound and Force Production of Flexible Insect Wings

Geng

Zheng

Xue

et al. 2018

Fluids

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We numerically solved the acoustic and flow field around cicada wing models with parametrically varied flexibility using the hydrodynamic/acoustic splitting method. We observed a gradual change of sound directivity with flexibility. We found that flexible wings generally produce lower sound due to reduced aerodynamic forces, which were further found to scale with the dynamic pressure force defined as the integration of dynamic pressure over the wing area. Unlike conventional scaling where the incoming flow velocity is used as the reference to calculate the force coefficients, here only the normal component of the relative velocity of the wing to the flow was used to calculate the dynamic pressure, putting kinematic factors into the dynamic pressure force and leaving the more fundamental physics to the force coefficients. A high correlation was found between the aerodynamic forces and the dynamic pressure. The scaling is also supported by previously reported data of revolving wing experiments.

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Section: ∇•supporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Numerical Study of the Sound and Force Production of Flexible Insect Wings

Geng

Zheng

Xue

et al. 2018

Fluids

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“…During a foil stroke, positive pressure is formed on the loading face due to fluid being displaced and negative pressure is formed on the opposite face mainly due to the leading-edge vortices. The positive and negative pressure exchange sides during the switch between the downstroke and the upstroke [41]. A clear illustration of the foil-loading mechanism can be found in the work by Inada et al [68].…”

Section: Propagation and Decay Of Pressure Wavesmentioning

confidence: 93%

“…However, the aeroacoustics induced by the flapping foil has not been well understood [41]. Although the high performance of insect flight can be achieved with low noises, the flapping sound generated by the foil may have potential effects on biological functions, such as the communication using aposematic signals with the locomotion-induced sound [41]. Moreover, the study on the sound induced by flapping foil may also have potential applications in medical inspections, such as the phonation of human which performs like a flapping foil induced sound [4].…”

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confidence: 99%

An immersed boundary method for fluid–structure–acoustics interactions involving large deformations and complex geometries

Wang

Tian

Lai

2020

Journal of Fluids and Structures

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This paper presents an immersed boundary (IB) method for fluid-structure-acoustics interactions involving large deformations and complex geometries. In this method, the fluid dynamics is solved by a finite difference method where the temporal, viscous and convective terms are respectively discretized by the third-order Runge-Kutta scheme, the fourth-order central difference scheme and a fifth-order W/TENO (Weighted/Targeted Essentially Non-oscillation) scheme. Without loss of generality, a nonlinear flexible plate is considered here, and is solved by a finite element method based on the absolute nodal coordinate formulation. The no-slip boundary condition at the fluid-structure interface is achieved by using a diffusion-interface penalty IB method. With the above proposed method, the aeroacoustics field generated by the moving boundaries and the associated flows are inherently solved. In order to validate and verify the current method, several benchmark cases are conducted: acoustic waves scattered from a stationary cylinder in a quiescent flow, sound generation by a stationary and a rotating cylinder in a uniform flow, sound generation by an insect in hovering flight, deformation of a red blood cell induced by acoustic waves and acoustic waves scattered by a stationary sphere. The comparison of the sound scattered by a cylinder shows that the present IB-WENO scheme, a simple approach, has an excellent performance which is even better than the implicit IB-lattice Boltzmann method. For the sound scattered by a sphere, the IB-TENO scheme has a lower dissipation compared with the IB-WENO scheme. Applications of this technique to model fluid-structure-acoustics interactions of flapping foils mimicking an insect wing section during forward flight and flapping foil energy harvester are also presented, considering the effects of foil shape and flexibility. The difference of the force and sound generations of the foils are compared. For wing during forward flight, the results show that flexible wing generates larger thrust with higher acoustic pressure. In terms of the energy harvester, the current results show that the geometrical shape has no significant effects on the force and sound generation, and the flexibility of the plate tends to deteriorate the power extraction efficiency. The flexible plate also induces larger fluctuating pressure at the frequency of 2f (f is the flapping frequency) and weaker sound at the frequencies of f and 3f . The successful validations and applications show that the IB method handled by delta function, whose accuracy is generally lower than that of the internal flow solver, is accurate for predicting the arXiv:1905.00182v1 [physics.flu-dyn] 1 May 2019An immersed boundary method for fluid-structure-acoustics interactions involving large deformations and complex geometries A PREPRINT dilatation and acoustics, and thus is an attractive alternative for modelling fluid-structure-acoustics interactions involving large deformations and complex geometries.Keywords Immersed boundary method · lar...

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