Thrust production and wake structure of a batoid-inspired oscillating fin

Clark, Richard K.; Smits, Alexander J.

doi:10.1017/s0022112006001297

Cited by 134 publications

(123 citation statements)

References 16 publications

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“…Other factors, such as stiffness of the tail, swimming frequency and Strouhal number may be responsible for differences in wake structure [32,33].…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2011

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Understanding how moving organisms generate locomotor forces is fundamental to the analysis of aerodynamic and hydrodynamic flow patterns that are generated during body and appendage oscillation. In the past, this has been accomplished using two-dimensional planar techniques that require reconstruction of three-dimensional flow patterns. We have applied a new, fully three-dimensional, volumetric imaging technique that allows instantaneous capture of wake flow patterns, to a classic problem in functional vertebrate biology: the function of the asymmetrical (heterocercal) tail of swimming sharks to capture the vorticity field within the volume swept by the tail. These data were used to test a previous three-dimensional reconstruction of the shark vortex wake estimated from two-dimensional flow analyses, and show that the volumetric approach reveals a different vortex wake not previously reconstructed from two-dimensional slices. The hydrodynamic wake consists of one set of dual-linked vortex rings produced per half tail beat. In addition, we use a simple passive shark-tail model under robotic control to show that the three-dimensional wake flows of the robotic tail differ from the active tail motion of a live shark, suggesting that active control of kinematics and tail stiffness plays a substantial role in the production of wake vortical patterns.

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“…Other factors, such as stiffness of the tail, swimming frequency and Strouhal number may be responsible for differences in wake structure [32,33].…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2011

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“…The efficiency of an oscillating, flexible hydrofoil is increased by 20% with a small decrease in thrust, compared to a rigid propulsor executing similar movements [13]. Furthermore, the presence of a traveling wave moving in the chordwise direction can increase efficiency and enhance swimming speed [53,54].…”

Section: Manta Efficiencymentioning

confidence: 99%

Hydrodynamic Performance of Aquatic Flapping: Efficiency of Underwater Flight in the Manta

et al. 2016

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Abstract:The manta is the largest marine organism to swim by dorsoventral oscillation (flapping) of the pectoral fins. The manta has been considered to swim with a high efficiency stroke, but this assertion has not been previously examined. The oscillatory swimming strokes of the manta were examined by detailing the kinematics of the pectoral fin movements swimming over a range of speeds and by analyzing simulations based on computational fluid dynamic potential flow and viscous models. These analyses showed that the fin movements are asymmetrical up-and downstrokes with both spanwise and chordwise waves interposed into the flapping motions. These motions produce complex three-dimensional flow patterns. The net thrust for propulsion was produced from the distal half of the fins. The vortex flow pattern and high propulsive efficiency of 89% were associated with Strouhal numbers within the optimal range (0.2-0.4) for rays swimming at routine and high speeds. Analysis of the swimming pattern of the manta provided a baseline for creation of a bio-inspired underwater vehicle, MantaBot.

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“…The stingray's undulatory body disc is a target of interest (Clark and Smits, 2006;Low and Willy, 2006), as is the oscillatory wing of manta rays (Punning et al, 2004;Gao et al, 2007;Wang et al, 2009). Robotic fins and the robots they propel provide important tools not only for engineers but also for biologists testing functional hypotheses (Lauder et al, 2007;Long, 2007).…”

Section: Design Of Electric-ray-inspired Underwater Robotsmentioning

confidence: 99%

Sink and swim: kinematic evidence for lifting-body mechanisms in negatively buoyant electric rays Narcine brasiliensis

Rosenblum

Long

Porter

2011

Journal of Experimental Biology

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SUMMARY Unlike most batoid fishes, electric rays neither oscillate nor undulate their body disc to generate thrust. Instead they use body–caudal–fin (BCF) locomotion. In addition, these negatively buoyant rays perform unpowered glides as they sink in the water column. In combination, BCF swimming and unpowered gliding are opposite ends on a spectrum of swimming, and electric rays provide an appropriate study system for understanding how the performance of each mode is controlled hydrodynamically. We predicted that the dorso-ventrally flattened body disc generates lift during both BCF swimming and gliding. To test this prediction, we examined 10 neonate lesser electric rays, Narcine brasiliensis, as they swam and glided. From video, we tracked the motion of the body, disc, pelvic fins and tail. By correlating changes in the motions of those structures with swimming performance, we have kinematic evidence that supports the hypothesis that the body disc is generating lift. Most importantly, both the pitch of the body disc and the tail, along with undulatory frequency, interact to control horizontal swimming speed and Strouhal number during BCF swimming. During gliding, the pitch of the body disc and the tail also interact to control the speed on the glide path and the glide angle.

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Thrust production and wake structure of a batoid-inspired oscillating fin

Cited by 134 publications

References 16 publications

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

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

Hydrodynamic Performance of Aquatic Flapping: Efficiency of Underwater Flight in the Manta

Sink and swim: kinematic evidence for lifting-body mechanisms in negatively buoyant electric rays Narcine brasiliensis

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