Volumetric imaging of shark tail hydrodynamics reveals a three-dimensional dual-ring vortex wake structure

Flammang, Brooke E.; Lauder, George V.; Troolin, Dan; Strand, T. E.

doi:10.1098/rspb.2011.0489

Cited by 72 publications

(65 citation statements)

References 46 publications

(60 reference statements)

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“…Such propulsion surfaces include dorsal fins [2][3][4] and pectoral fins [5][6][7] in body and caudal fin (BCF) propulsion and ribbon fins [8][9][10] in median and paired fin (MPF) propulsion. As the most conspicuous appendage of the fish's body, the caudal fin has also been studied extensively [11][12][13][14][15]. The use of bio-inspired devices has been one of the most pervasive methods for achieving insight into the hydrodynamic performance of the caudal fin [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Fish Caudal Fin Locomotion Using a Bio-Inspired Robotic Model

Wang

Wen

2016

International Journal of Advanced Robotic Systems

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Due to its advantages of realizing repeatable experiments, collecting data and isolating key factors, the bio-robotic model is becoming increasingly important in the study of biomechanics. The caudal fin of fish has long been understood to be central to propulsion performance, yet its contribution to manoeuverability, especially for homocercal caudal fin, has not been studied in depth. In the research outlined in this paper, we designed and fabricated a robotic caudal fin to mimic the morphology and the three-dimensional (3D) locomotion of the tail of the Bluegill Sunfish (Lepomis macrochirus). We applied heave and pitch motions to the robot to model the movement of the caudal peduncle of its biological counterpart. Force measurements and 2D and 3D digital particle image velocimetry were then conducted under different movement patterns and flow speeds. From the force data, we found the addition of the 3D caudal fin locomotion significantly enhanced the lift force magnitude. The phase difference between the caudal fin ray and peduncle motion was a key factor in simultaneously controlling the thrust and lift. The increased flow speed had a negative impact on the generation of lift force. From the average 2D velocity field, we observed that the vortex wake directed water both axially and vertically, and formed a jet-like structure with notable wake velocity. The 3D instantaneous velocity field at 0.6 T indicated the 3D motion of the caudal fin may result in asymmetry wake flow patterns relative to the mid-sagittal plane and change the heading direction of the shedding vortexes. Based on these results, we hypothesized that live fish may actively tune the movement between the caudal fin rays and the peduncle to change the wake structure behind the tail and hence obtain different thrust and lift forces, which contributes to its high manoeuvrability.

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Section: Introductionmentioning

confidence: 99%

Investigation of Fish Caudal Fin Locomotion Using a Bio-Inspired Robotic Model

Wang

Wen

2016

International Journal of Advanced Robotic Systems

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“…Like the dorsal and anal fins in bluegill sunfish (Drucker and Lauder, 2001;Tytell, 2006), the vortices of the second dorsal fin in spiny dogfish appear to interact with the tail, although further research using three-dimensional vortex reconstruction (see Tytell, 2006) is necessary to fully demonstrate the extent to which three-dimensional vortices encounter the tail and modify flows generated there. In spiny dogfish, the tail vortices have been previously described as having a ring-within-a-ring vortex structure (see Flammang et al, 2011;Wilga and Lauder, 2004a). The complex shape of shark tail vortices may be due to the heterocercal shape, but could also be in part an effect of vorticity entrained from the wake of the second dorsal fin.…”

Section: Dorsal Fin Functionmentioning

confidence: 99%

Hydrodynamic function of dorsal fins in spiny dogfish and bamboo sharks during steady swimming

Maia

Lauder

Wilga

2017

Journal of Experimental Biology

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A key feature of fish functional design is the presence of multiple fins that allow thrust vectoring and redirection of fluid momentum to contribute to both steady swimming and maneuvering. A number of previous studies have analyzed the function of dorsal fins in teleost fishes in this context, but the hydrodynamic function of dorsal fins in freely swimming sharks has not been analyzed, despite the potential for differential functional roles between the anterior and posterior dorsal fins. Previous anatomical research has suggested a primarily stabilizing role for shark dorsal fins. We evaluated the generality of this hypothesis by using time-resolved particle image velocimetry to record water flow patterns in the wake of both the anterior and posterior dorsal fins in two species of freely swimming sharks: bamboo sharks (Chiloscyllium plagiosum) and spiny dogfish (Squalus acanthias). Cross-correlation analysis of consecutive images was used to calculate stroke-averaged mean longitudinal and lateral velocity components, and vorticity. In spiny dogfish, we observed a velocity deficit in the wake of the first dorsal fin and flow acceleration behind the second dorsal fin, indicating that the first dorsal fin experiences net drag while the second dorsal fin can aid in propulsion. In contrast, the wake of both dorsal fins in bamboo sharks displayed increased net flow velocity in the majority of trials, reflecting a thrust contribution to steady swimming. In bamboo sharks, fluid flow in the wake of the second dorsal fin had higher absolute average velocity than that for first dorsal fin, and this may result from a positive vortex interaction between the first and second dorsal fins. These data suggest that the first dorsal fin in spiny dogfish has primarily a stabilizing function, while the second dorsal fin has a propulsive function. In bamboo sharks, both dorsal fins can contribute thrust and should be considered as propulsive adjuncts to the body during steady swimming. The function of shark dorsal fins can thus differ considerably among fins and species, and is not limited to a stabilizing role.

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“…But in the same experimental environment [8], the coefficient of fluid resistance, the density of fluid and the surface area of fish are small, so they can be regarded as constants [9]. Now the product of c is the product of the three.…”

Section: The Relationship Between the Oscillating Frequency Of The Camentioning

confidence: 99%

“…After hundreds of millions years of evolution, fishes have different tail fins of different shapes and flexibility [8], and the shape of the caudal fin is often represented by a formula (1):…”

Section: Fig1 External Structure Of Biomimetic Fishmentioning

confidence: 99%

A new type of biomimetic fish with oscillatory propulsion method

Zhang

Deng

et al. 2017

MATEC Web Conf.

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Abstract. The traditional multi joint mechanical serial parallel structure biomimetic fish has lower propulsive efficiency, more energy transmission loss, more complicated mechanical design and control algorithms because of more mechanical joints. While the flexible body has infinite degrees of freedom, and the energy in it is stored by elasticity and inertia, it is more viscous than that of multi joints. This project studies the principle of carangidae fish in carangidae carp, takes it as the bionic object, and designs a biomimetic fish with a flexible body tail structure to improve propulsive efficiency. This study explores the biomimetic fish propulsion speed and caudal aspect ratio, caudal oscillation frequency, modal distribution curve, and optimizes a parameter set of fish tail that can achieve effective promotion. So it is good for the exploration of the development of high speed, high efficiency, high maneuverability of bionic propeller swing on theoretical basis and practical aspects.

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Volumetric imaging of shark tail hydrodynamics reveals a three-dimensional dual-ring vortex wake structure

Cited by 72 publications

References 46 publications

Investigation of Fish Caudal Fin Locomotion Using a Bio-Inspired Robotic Model

Investigation of Fish Caudal Fin Locomotion Using a Bio-Inspired Robotic Model

Hydrodynamic function of dorsal fins in spiny dogfish and bamboo sharks during steady swimming

A new type of biomimetic fish with oscillatory propulsion method

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