Fluid mechanics of flapping wings

Ellenrieder, Karl D. von; Parker, Kamalluddien; Soria, Julio

doi:10.1016/j.expthermflusci.2008.05.003

Cited by 49 publications

(36 citation statements)

References 65 publications

(131 reference statements)

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“…Bohl and Koochesfahani [10] experimentally studied the RKVS with various reduced frequencies. Ellenrieder et al [11] explained the Strouhal number dependency of the wake vortex structure behind a translating airfoil. Meanwhile, many researchers investigated the RKVS in different situations, such as the wakes of fishes [12,13] in both experiments [14][15][16] and numerical simulations [16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis on transitions and symmetry-breaking in the wake of a flapping foil

Wang

Zhang

et al. 2012

Acta Mech Sin

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Flying and marine animals often use flapping wings or tails to generate thrust. In this paper, we will use the simplest flapping model with a sinusoidal pitching motion over a range of frequency and amplitude to investigate the mechanism of thrust generation. Previous work focuses on the Karman vortex street and the reversed Karman vortex street but the transition between two states remains unknown. The present numerical simulation provides a complete scenario of flow patterns from the Karman vortex street to reversed Karman vortex street via aligned vortices and the ultimate state is the deflected Karman vortex street, as the parameters of flapping motions change. The results are in agreement with the previous experiment. We make further discussion on the relationship of the observed states with drag and thrust coefficients and explore the mechanism of enhanced thrust generation using flapping motions.

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Section: Introductionmentioning

confidence: 99%

Numerical analysis on transitions and symmetry-breaking in the wake of a flapping foil

Wang

Zhang

et al. 2012

Acta Mech Sin

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“…In particular, it is important to understand how aerodynamic forces are generated and to use this knowledge for the improvement of simplified force models. There is a broad literature on the aerodynamics of flapping wings as recently reviewed by several authors [Rozhdestvensky and Ryzhov, 2003, Platzer et al, 2008, von Ellenrieder et al, 2008, Shyy et al, 2010, 2013.…”

Section: Introductionmentioning

confidence: 99%

On the aerodynamic forces on heaving and pitching airfoils at low Reynolds number

2017

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The influence that the kinematics of pitching and heaving 2D airfoils have on the aerodynamic forces is investigated using Direct Numerical Simulations and a force decomposition algorithm. Large amplitude motions are considered (of the order of one chord), with moderate Reynolds numbers and reduced frequencies of order O(1), varying the mean pitch angle and the phase shift between the pitching and heaving motions. Our results show that the surface vorticity contribution (viscous effects) to the aerodynamic force is negligible compared to the contributions from the body motion (fluid inertia) and the vorticity within the flow (circulation). For the range of parameters considered here, the latter tends to be instantaneously oriented in the direction normal to the chord of the airfoil. Based on the results discussed in the paper, a reduced order model for the instantaneous aerodynamic force is proposed, taking advantage of the force decomposition and the chord-normal orientation of the contribution from vorticity within the flow to the total aerodynamic force. The predictions of the proposed model are compared to those of a similar model from the literature, showing a noticeable improvement on the prediction of the mean thrust, and a smaller improvement on the prediction of mean lift and the instantaneous force coefficients.

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“…The current understanding of the physics of thrust generation in air was specifically presented having in mind possible technology applications, such as micro air vehicles (MAVs). The fluid-structure interaction problem for flapping flight was instead discussed in some detail by van Ellenrieder et al [4]: the hypothesis that the Strouhal number selection in natural flapping flight is a limit cycle process was proposed in such a discussion. The wake behind oscillating wings and its relation to the thrust generated by the wing's motion has also been extensively studied for a number of years, e.g.…”

Section: Introductionmentioning

confidence: 98%