The performance of a flapping foil for a self-propelled fishlike body

Paniccia, Damiano; Padovani, Luca; Graziani, G.; Piva, R.

doi:10.1038/s41598-021-01730-4

Cited by 10 publications

(6 citation statements)

References 41 publications

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“…As a general comment, it is worth to underline the tendency of the fluid recoil to enhance the heave amplitude up to a value strictly comparable with the trailing edge excursion A te as shown by the increase of the ratio A h /A te which represents the fraction of the trailing edge amplitude due to the heave motion of the peduncle. The more A h /A te approaches unity, the more the caudal fin is flat at its maximum lateral position, so to lay, together with the anterior body, on the sinusoidal trajectory and to obtain a good swimming performance [9,43]. Actually, the relationship between a high swimming performance and a flat tail excursion was already envisaged in the early sixties by Lighthill [15] who suggested to annihilate the slope of the midline amplitude modulation to maximize the swimming efficiency.…”

Section: Discussionmentioning

confidence: 99%

“…The performance of these oscillatory swimmers has been usually evaluated by the Froude efficiency of the flapping foil propulsor, with assigned heave and pitch motions, under a prescribed uniform stream [1][2][3][4][5][6] or by the cost of transport for the whole body, consisting of a flapping foil plus a resistant virtual body, self-propelled in axial mode [7,8]. A comparative analysis of the above two parameters for evaluating the swimming performance has been deeply analyzed to prove their suitability for different swimming gaits [9,10]. The above procedures are both very convenient for experimental and numerical investigations, but unable to account for the actual motion of the fishlike body in free swimming mode and for its presumed impact on the overall performance [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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Locomotion performance for oscillatory swimming in free mode

et al. 2022

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Oscillatory swimming of a fishlike body, whose motion is essentially promoted by the flapping tail, has been studied almost exclusively in axial mode under an incoming uniform stream or, more recently, self-propelled under a virtual body resistance. Obviously, both approaches do not consider the unavoidable recoil motions of the actual body which have to be necessarily accounted for in a design procedure for technological means. Actually, once combined with the prescribed kinematics of the tail, the recoil motions have an essential impact on the resulting swimming performance. An inviscid impulse model, linear in both potential and vortical contributions, is a proper tool to obtain a deeper comprehension of the physical events with respect to more elaborated flow interaction models. In fact, at a first look, the numerical results seem to be quite entangled, since their trends in terms of the main flapping parameters are not easy to be identified and a fair interpretation is obtained by means of the model capability to separate the effects of added mass and vortex shedding. Specifically, a prevailing dependence of the potential contribution on the heave amplitude and of the vortical contribution on the pitch amplitude is instrumental to unravel their combined action. A further aid for a proper interpretation of the data is provided by accounting separately for a geometrical component of the recoil which is expected to follow from the annihilation of any spurious rigid motion in case no fluid interactions occur. The above detailed decomposition of the recoil motions shows, through the numerical results, how the single components are going to influence the main flapping parameters and the locomotion performance as a guide for the design of biomimetic swimmers.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Locomotion performance for oscillatory swimming in free mode

et al. 2022

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“…Other studies have focused on flexible foil propulsion, using simple passively bending polymeric representations of the fish body and tail moved in heave and/or pitch at the leading edge [46,54,55] to generate an undulatory propulsive wave down the foil. Much of this previous work has involved foils with uniform material properties along their length, as have recent computational studies of flapping foil propulsion [56].…”

Section: Efficient Foil Propulsionmentioning

confidence: 99%

Role of the caudal peduncle in a fish-inspired robotic model: how changing stiffness and angle of attack affects swimming performance

Matthews¹,

Zhu²,

Wang³

et al. 2022

Bioinspir. Biomim.

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The tail in fishes is a key element of propulsive anatomy that contributes to thrust during swimming. Fishes possess the ability to alter tail stiffness, surface area, and conformation. Specifically, the region at the base of the tail, the caudal peduncle, is proposed to be key location of fish stiffness modulation during locomotion. Most previous analyses have focused on overall body or tail stiffness, and not on the effects of changing stiffness specifically at the base of the tail in fishes and robotic models. We used both computational fluid dynamic analysis and experimental measurements of propulsive forces in physical models with different peduncle stiffnesses to analyze the effect of altering stiffness on the tail angle of attack and propulsive forces and efficiency. By changing the motion program input to the tail, we were able to alter the phase relationship between front and back tail sections between 0 and 330 degrees. Computational simulations showed that power consumption was nearly minimized and thrust production nearly maximized at the kinematic pattern where ϕ = 270°, the approximate phase lag observed in the experimental foils. We observed reduced thrust and efficiency at high angles of attack suggesting that the tail driven at these motion programs experiences stall and loss of lift. However, there was no single peduncle stiffness that consistently maximized performance, particularly in physical models. This result highlights the fact that optimal caudal peduncle stiffness is highly context dependent. Therefore, incorporating the ability to control peduncle stiffness in future robotic models of fish propulsion promises to increase the ability of robots to approach the performance of fishes.

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“…Many natural swimmers use flapping fins and tails for their locomotion (Webb, 1975;Alexander, 2003). This common strategy for natural aquatic locomotion has motivated researchers around the world to analyze the efficient thrust generation of rigid flapping foils during the past few decades (Lighthill, 1970;Wu, 1971;Triantafyllou et al, 1993;Anderson et al, 1998;Young and Lai, 2007;Mackowski and Williamson, 2015;Fernandez-Feria, 2017;Paniccia et al, 2021), and to develop bioinspired underwater vehicles self propelled by flapping foils (Triantafyllou and Triantafyllou, 1995;Lauder et al, 2007;Wen et al, 2012;Gibouin et al, 2018;Zhu et al, 2019;Sánchez-Rodríguez et al, 2021).…”

Section: Introductionmentioning

confidence: 99%