Labriform propulsion in fishes: kinematics of flapping aquatic flight in the bird wrasse Gomphosus varius (Labridae)

1997 ◽  
Vol 200 (11) ◽  
pp. 1549-1569 ◽  
Author(s):  
J Walker ◽  
M Westneat
Keyword(s):  
Center Of Mass ◽  
Three Dimensional ◽  
Lateral View ◽  
Pectoral Fin ◽  
Pectoral Fins ◽  
Video Images ◽  
Stationary Observer ◽  
Swimming Mode ◽  
Total Body ◽  
Unsteady Effects

Labriform, or pectoral fin, propulsion is the primary swimming mode for many fishes, even at high relative speeds. Although kinematic data are critical for evaluating hydrodynamic models of propulsion, these data are largely lacking for labriform swimmers, especially for species that employ an exclusively labriform mode across a broad range of speeds. We present data on pectoral fin locomotion in Gomphosus varius (Labridae), a tropical coral reef fish that uses a lift-based mechanism to fly under water at sustained speeds of 1­6 total body lengths s-1 (TL s-1). Lateral- and dorsal-view video images of three fish swimming in a flow tank at 1­4 TL s-1 were recorded at 60 Hz. From the two views, we reconstructed the three-dimensional motion of the center of mass, the fin tip and two fin chords for multiple fin beats of each fish at each of four speeds. In G. varius, the fin oscillates largely up and down: the stroke plane is tilted by approximately 20 ° from the vertical. Both frequency and the area swept by the pectoral fins increase with swimming speed. Interestingly, there are individual differences in how this area increases. Relative to the fish, the fin tip in lateral view moves along the path of a thin, inclined figure-of-eight. Relative to a stationary observer, the fin tip traces a sawtooth pattern, but the teeth are recumbent (indicating net backwards movement) only at the slowest speeds. Distal fin chords pitch nose downward during the downstroke and nose upward during the upstroke. Hydrodynamic angles of attack are largely positive during the downstroke and negative during the upstroke. The geometry of the fin and incident flow suggests that the fin is generating lift with large upward and small forward components during the downstroke. The negative incident angles during the upstroke suggest that the fin is generating largely thrust during the upstroke. In general, the large thrust is combined with a downward force during the upstroke, but the net backwards motion of the fin at slow speeds generates a small upward component during slow swimming. Both the alternating sign of the hydrodynamic angle of attack and the observed reduced frequencies suggest that unsteady effects are important in G. varius aquatic flight, especially at low speeds. This study provides a framework for the comparison of aquatic flight by fishes with aerial flight by birds, bats and insects.

Fluid dynamics of flapping aquatic flight in the bird wrasse:three-dimensional unsteady computations with fin deformation

2002 ◽  
Vol 205 (19) ◽  
pp. 2997-3008 ◽  
Author(s):  
Ravi Ramamurti ◽  
William C. Sandberg ◽  
Rainald Löhner ◽  
Jeffrey A. Walker ◽  
Mark W. Westneat
Keyword(s):  
Fluid Dynamics ◽  
Steady State ◽  
Three Dimensional ◽  
Force Production ◽  
Time History ◽  
The Body ◽  
Vertical Acceleration ◽  
Field Variation ◽  
Pectoral Fin ◽  
Pectoral Fins

SUMMARY Many fishes that swim with the paired pectoral fins use fin-stroke parameters that produce thrust force from lift in a mechanism of underwater flight. These locomotor mechanisms are of interest to behavioral biologists,biomechanics researchers and engineers. In the present study, we performed the first three-dimensional unsteady computations of fish swimming with oscillating and deforming fins. The objective of these computations was to investigate the fluid dynamics of force production associated with the flapping aquatic flight of the bird wrasse Gomphosus varius. For this computational work, we used the geometry of the wrasse and its pectoral fin,and previously measured fin kinematics, as the starting points for computational investigation of three-dimensional (3-D) unsteady fluid dynamics. We performed a 3-D steady computation and a complete set of 3-D quasisteady computations for a range of pectoral fin positions and surface velocities. An unstructured, grid-based, unsteady Navier—Stokes solver with automatic adaptive remeshing was then used to compute the unsteady flow about the wrasse through several complete cycles of pectoral fin oscillation. The shape deformation of the pectoral fin throughout the oscillation was taken from the experimental kinematics. The pressure distribution on the body of the bird wrasse and its pectoral fins was computed and integrated to give body and fin forces which were decomposed into lift and thrust. The velocity field variation on the surface of the wrasse body, on the pectoral fins and in the near-wake was computed throughout the swimming cycle. We compared our computational results for the steady, quasi-steady and unsteady cases with the experimental data on axial and vertical acceleration obtained from the pectoral fin kinematics experiments. These comparisons show that steady state computations are incapable of describing the fluid dynamics of flapping fins. Quasi-steady state computations, with correct incorporation of the experimental kinematics, are useful when determining trends in force production, but do not provide accurate estimates of the magnitudes of the forces produced. By contrast, unsteady computations about the deforming pectoral fins using experimentally measured fin kinematics were found to give excellent agreement, both in the time history of force production throughout the flapping strokes and in the magnitudes of the generated forces.

Upper Extremity Function in Running. II: Angular Momentum Considerations

1987 ◽  
Vol 3 (3) ◽  
pp. 242-263 ◽  
Author(s):  
Richard N. Hinrichs
Keyword(s):  
Angular Momentum ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Vertical Component ◽  
The Body ◽  
Lower Trunk ◽  
Body Center ◽  
Recreational Runners ◽  
Total Body ◽  
Angular Impulse

Ten male recreational runners were filmed using three-dimensional cinematography while running on a treadmill at 3.8 m/s, 4.5 m/s, and 5.4 m/s. A 14-segment mathematical model was used to examine the contributions of the arms to the total-body angular momentum about three orthogonal axes passing through the body center of mass. The results showed that while the body possessed varying amounts of angular momentum about all three coordinate axes, the arms made a meaningful contribution to only the vertical component (Hz). The arms were found to generate an alternating positive and negative Hzpattern during the running cycle. This tended to cancel out an opposite Hzpattern of the legs. The trunk was found to be an active participant in this balance of angular momentum, the upper trunk rotating back and forth with the arms and, to a lesser extent, the lower trunk with the legs. The result was a relatively small total-body Hzthroughout the running cycle. The inverse relationship between upper- and lower-body angular momentum suggests that the arms and upper trunk provide the majority of the angular impulse about the z axis needed to put the legs through their alternating strides in running.

Bioinspiration From Flexible Propulsors: Organismal Design, Mechanical Properties, Kinematics and Neurobiology of Pectoral Fins in Labrid Fishes

2017 ◽  
Vol 51 (5) ◽  
pp. 23-34 ◽  
Author(s):  
Mark W. Westneat ◽  
Brett R. Aiello ◽  
Aaron M. Olsen ◽  
Melina E. Hale
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
High Performance ◽  
Neural Control ◽  
Three Dimensional ◽  
Marine Species ◽  
Flexural Stiffness ◽  
Pectoral Fin ◽  
Pectoral Fins ◽  
Flexible Fin

AbstractLabrid fishes use their pectoral fins for efficient high-speed cruising behavior, as well as for precision maneuvering in complex environments, making them good models for biomimicry applications in propulsor technology for aquatic vehicles. Lift-based labriform locomotion is a form of aquatic flight used by many species and is the sole mode of transport across most speeds by some of the largest wrasses and parrotfishes on coral reefs. Although basic and applied research has explored fin design in several species utilizing labriform propulsion, a detailed analysis of fin anatomy, fin mechanical properties, and well-resolved three-dimensional (3D) kinematics in high-performance aquatic flyers has not yet been attained. Here, we present recent research on fin structure, fin flexural stiffness, sensory abilities of fins, and a novel 3D approach to flexible fin kinematics. Our aims are to outline important future directions for this field and to assist engineers attempting biomimicry of maneuverable fin-based locomotion for applications in robotics. First, we illustrate the anatomical structure and branching patterns of the pectoral fin skeleton and the muscles that drive fin motion. Second, we present data on the flexural stiffness of pectoral fins in the parrotfish (Scarus quoyi), setting up a stiffness field that gives the fin propulsor its passive mechanical properties and enables hydrodynamically advantageous fin deformations during swimming. Third, we present 3D reconstructions of the kinematics of high-performance Scarus fins that greatly enhance our ability to reproduce fin motions for engineering applications and also yield insight into the functional role of the fin stiffness field. Lastly, recent work on mechanosensation is illustrated as key to understanding sensorimotor control of labriform locomotion. Research on pectoral fin structure, function, and neural control in large marine species with high-performance wing-like fins is important to the comparative biology of locomotion in fishes, and we suggest it is a productive area of research on fin function for applications in the design of quiet, efficient propulsors.

Mechatronic Design and Maneuverability Analysis of a Novel Robotic Shark for Coral Reef Detection

2021 ◽  
Author(s):  
Liyang Gao ◽  
Peng Li ◽  
Hongde Qin ◽  
Zhongchao Deng
Keyword(s):  
Coral Reef ◽  
Dynamic Model ◽  
Swimming Speed ◽  
Three Dimensional ◽  
Pectoral Fin ◽  
Spiral Motion ◽  
Pectoral Fins ◽  
Mechatronic Design ◽  
Grid Technique ◽  
Turning Radius

Abstract In this paper, mechatronic design of a novel robotic shark for coral reef detection is presented. To obtain good maneuverability, a barycenter regulating device is designed to assist the posture adjustment of the robotic shark at low speed. Based on STAR-CCM+ software, the lift coefficients and drag coefficients of pectoral fin are calculated using overlapping grid technique. Based on Newton-Euler approach, a dynamic model with particular consideration of pectoral fins for three-dimensional motion is established. A CPG controller is used to generate rhythmic motion of each joint. Furthermore, based on the dynamic model, three-dimensional trajectory of spiral motion and swimming speed in different oscillation parameters are simulated. The results show that swimming speed of the robotic shark can be improved by increasing the amplitude and frequency or decreasing the phase difference. Also, oscillation frequency plays a more significant role. Furthermore, under the action of single pectoral fin, the robotic shark can achieve spiral motion and the turning radius is about 35.8m under the parameters set in this article.

Numerical Study of Batoid with Asymmetrically Undulating Pectoral Fins

2013 ◽  
Vol 307 ◽  
pp. 89-96
Author(s):  
Zhi Jun Wu ◽  
Wei Shan Chen ◽  
Jun Kao Liu ◽  
Sheng Jun Shi
Keyword(s):  
Dynamic Simulation ◽  
Numerical Study ◽  
Swimming Performance ◽  
Three Dimensional ◽  
Dynamic Parameters ◽  
Pectoral Fin ◽  
Symmetric Motion ◽  
Pectoral Fins ◽  
Simulation Results ◽  
The Difference

This paper presents a numerical study of three dimensional flows around a self-propelled batoid with asymmetrically undulating pectoral fins. During the dynamic simulation, the difference of phase angle of the asymmetric motion is set to 180° between left pectoral fin and right pectoral fin. To evaluate the swimming performance of batoid with asymmetric undulating fins, kinematic and dynamic parameters have been used comparing with that of batoid with symmetric undulating fins. The simulation results show that asymmetric motion can achieve better starting and accelerating performance than symmetric motion.

scholarly journals Three-dimensional kinematics and wake structure of the pectoral fins during locomotion in leopard sharks Triakis semifasciata

2000 ◽  
Vol 203 (15) ◽  
pp. 2261-2278 ◽  
Author(s):  
C.D. Wilga ◽  
G.V. Lauder
Keyword(s):  
Water Column ◽  
Three Dimensional ◽  
The Body ◽  
Force Balance ◽  
Body Tilt ◽  
Pectoral Fin ◽  
Body Angle ◽  
Pectoral Fins ◽  
Triakis Semifasciata ◽  
Leopard Sharks

The classical theory of locomotion in sharks proposes that shark pectoral fins are oriented to generate lift forces that balance the moment produced by the oscillating heterocercal tail. Accordingly, previous studies of shark locomotion have used fixed-wing aircraft as a model assuming that sharks have similar stability and control mechanisms. However, unlike airplanes, sharks are propelled by undulations of the body and tail and have considerable control of pectoral fin motion. In this paper, we use a new approach to examine the function of the pectoral fins of leopard sharks, Triakis semifasciata, during steady horizontal swimming at speeds of 0.5-2.0ls(−1), where l is total body length, and during vertical maneuvering (rising and sinking) in the water column. The planar orientation of the pectoral fin was measured using three-dimensional kinematics, while fluid flow in the wake of the pectoral fin and forces exerted on the water by the fin were quantified using digital particle image velocimetry (DPIV). Steady horizontal swimming in leopard sharks is characterized by continuous undulations of the body with a positive body tilt to the flow that decreases from a mean of 11 degrees to 0.6 degrees with increasing flow speeds from 0. 5 to 2.0ls(−1). Three-dimensional analysis showed that, during steady horizontal locomotion, the pectoral fins are cambered, concave downwards, at a negative angle of attack that we predict to generate no significant lift. Leopard shark pectoral fins are also oriented at a substantial negative dihedral angle that amplifies roll moments and hence promotes rapid changes in body position. Vortices shed from the trailing edge of the pectoral fin were detected only during vertical maneuvering. Starting vortices are produced when the posterior plane of the pectoral fin is actively flipped upwards or downwards to initiate rising or sinking, respectively, in the water column. The starting vortex produced by the pectoral fin induces a pitching moment that reorients the body relative to the flow. Body and pectoral fin surface angle are altered significantly when leopard sharks change vertical position in the water column. Thus, locomotion in leopard sharks is not analogous to flight in fixed-wing aircraft. Instead, a new force balance for swimming leopard sharks is proposed for steady swimming and maneuvering. Total force balance on the body is adjusted by altering the body angle during steady swimming as well as during vertical maneuvering, while the pectoral fins appear to be critical for initiating maneuvering behaviors, but not for lift production during steady horizontal locomotion.

scholarly journals Boxfishes (Teleostei: Ostraciidae) as a model system for fishes swimming with many fins: kinematics

2001 ◽  
Vol 204 (8) ◽  
pp. 1459-1471 ◽  
Author(s):  
J.R. Hove ◽  
L.M. O'Bryan ◽  
M.S. Gordon ◽  
P.W. Webb ◽  
D. Weihs
Keyword(s):  
Body Length ◽  
Total Body Length ◽  
Model System ◽  
Pectoral Fin ◽  
Forward Motion ◽  
Pectoral Fins ◽  
Refractory Periods ◽  
The Third ◽  
Stable Manner ◽  
Total Body

Swimming movements in boxfishes were much more complex and varied than classical descriptions indicated. At low to moderate rectilinear swimming speeds (<5 TL s(−1), where TL is total body length), they were entirely median- and paired-fin swimmers, apparently using their caudal fins for steering. The pectoral and median paired fins generate both the thrust needed for forward motion and the continuously varied, interacting forces required for the maintenance of rectilinearity. It was only at higher swimming speeds (above 5 TL s(−1)), when burst-and-coast swimming was used, that they became primarily body and caudal-fin swimmers. Despite their unwieldy appearance and often asynchronous fin beats, boxfish swam in a stable manner. Swimming boxfish used three gaits. Fin-beat asymmetry and a relatively non-linear swimming trajectory characterized the first gait (0--1 TL s(−1)). The beginning of the second gait (1--3 TL s(−1)) was characterized by varying fin-beat frequencies and amplitudes as well as synchrony in pectoral fin motions. The remainder of the second gait (3--5 TL s(−1)) was characterized by constant fin-beat amplitudes, varying fin-beat frequencies and increasing pectoral fin-beat asynchrony. The third gait (>5 TL s(−1)) was characterized by the use of a caudal burst-and-coast variant. Adduction was always faster than abduction in the pectoral fins. There were no measurable refractory periods between successive phases of the fin movement cycles. Dorsal and anal fin movements were synchronized at speeds greater than 2.5 TL s(−1), but were often out of phase with pectoral fin movements.

scholarly journals Locomotion in sturgeon: function of the pectoral fins

1999 ◽  
Vol 202 (18) ◽  
pp. 2413-2432 ◽  
Author(s):  
C.D. Wilga ◽  
G.V. Lauder
Keyword(s):  
Water Column ◽  
Three Dimensional ◽  
Total Body Length ◽  
The Body ◽  
Force Balance ◽  
Propulsive Force ◽  
Pectoral Fin ◽  
Posterior Portion ◽  
Body Angle ◽  
Pectoral Fins

Pectoral fins are one of the major features of locomotor design in ray-finned fishes and exhibit a well-documented phylogenetic transition from basal to derived clades. In percomorph fishes, the pectoral fins are often used to generate propulsive force via oscillatory movements, and pectoral fin propulsion in this relatively derived clade has been analyzed extensively. However, in the plesiomorphic pectoral fin condition, exemplified by sturgeon, pectoral fins extend laterally from the body in a generally horizontal orientation, have been assumed to generate lift to balance lift forces and moments produced by the heterocercal tail, and are not oscillated to generate propulsive force. The proposal that pectoral fins in fishes such as sturgeon generate lift during horizontal locomotion has never been tested experimentally in freely swimming fishes. In this paper, we examine the function of pectoral fins in sturgeon swimming at speeds from 0.5-3.0 L s(−)(1), where L is total body length. Sturgeon were studied during steady horizontal locomotion as well as while sinking and rising in the water column. Pectoral fin function was quantified using three-dimensional kinematics to measure the orientation of the fin surface, digital particle image velocimetry (DPIV) was used to describe flow in the wake of the fin and to estimate force exerted on the water, and electromyography was used to assess pectoral fin muscle function. Sturgeon (size range 25–32 cm total length) swam horizontally using continuous undulations of the body with a positive body angle that decreased from a mean of 20 degrees at 0.5 L s(−)(1) to 0 degrees at 3.0 L s(−)(1). Both the angle of the body and the pectoral fin surface angle changed significantly when sturgeon moved vertically in the water column. Three-dimensional kinematic analysis showed that during steady horizontal swimming the pectoral fins are oriented with a negative angle of attack predicted to generate no significant lift. This result was confirmed by DPIV analysis of the pectoral fin wake, which only revealed fin vortices, and hence force generation, during maneuvering. The orientation of the pectoral fins estimated by a two-dimensional analysis alone is greatly in error and may have contributed to previous suggestions that the pectoral fins are oriented to generate lift. Combined electromyographic and kinematic data showed that the posterior half of the pectoral fin is actively moved as a flap to reorient the head and body to initiate rising and sinking movements. A new force balance for swimming sturgeon is proposed for steady swimming and vertical maneuvering. During steady locomotion, the pectoral fins generate no lift and the positive body angle to the flow is used both to generate lift and to balance moments around the center of mass. To initiate rising or sinking, the posterior portion of the pectoral fins is actively moved ventrally or dorsally, respectively, initiating a starting vortex that, in turn, induces a pitching moment reorienting the body in the flow. Adjustments to body angle initiated by the pectoral fins serve as the primary means by which moments are balanced.

Center of Mass Theorem and the Separation of Variables for Two-Body System on a Three-Dimensional Sphere

2020 ◽  
Vol 23 (3) ◽  
pp. 306-311
Author(s):  
Yu. Kurochkin ◽  
Dz. Shoukavy ◽  
I. Boyarina
Keyword(s):  
Constant Curvature ◽  
Jacobi Equation ◽  
Separation Of Variables ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Relative Distance ◽  
Dimensional Sphere ◽  
Body System ◽  
Spaces Of Constant Curvature ◽  
Hamilton Jacobi Equation

The immobility of the center of mass in spaces of constant curvature is postulated based on its definition obtained in [1]. The system of two particles which interact through a potential depending only on the distance between particles on a three-dimensional sphere is considered. The Hamilton-Jacobi equation is formulated and its solutions and trajectory equations are found. It was established that the reduced mass of the system depends on the relative distance.

Design and Dynamic Modeling of a Flexible Feathering Joint for Robotic Fish Pectoral Fins

2014 ◽  
Author(s):  
Sanaz Bazaz Behbahani ◽  
Xiaobo Tan
Keyword(s):  
Dynamic Model ◽  
Robotic Fish ◽  
Power Stroke ◽  
Hydrodynamic Drag ◽  
Pectoral Fin ◽  
Flexible Joint ◽  
Blade Element Theory ◽  
Pectoral Fins ◽  
Flexible Part ◽  
Recovery Stroke

In this paper, we propose a novel design for a pectoral fin joint of a robotic fish. This joint uses a flexible part to enable the rowing pectoral fin to feather passively and thus reduce the hydrodynamic drag in the recovery stroke. On the other hand, a mechanical stopper allows the fin to maintain its motion prescribed by the servomotor in the power stroke. The design results in net thrust even when the fin is actuated symmetrically for the power and recovery strokes. A dynamic model for this joint and for a pectoral fin-actuated robotic fish involving such joints is presented. The pectoral fin is modeled as a rigid plate connected to the servo arm through a pair of torsional spring and damper that describes the flexible joint. The hydrodynamic force on the fin is evaluated with blade element theory, where all three components of the force are considered due to the feathering degree of freedom of the fin. Experimental results on robotic fish prototype are provided to support the effectiveness of the design and the presented dynamic model. We utilize three different joints (with different sizes and different flexible materials), produced with a multi-material 3D printer, and measure the feathering angles of the joints and the forward swimming velocities of the robotic fish. Good match between the model predictions and experimental data is achieved, and the advantage of the proposed flexible joint over a rigid joint, where the power and recovery strokes have to be actuated at different speeds to produce thrust, is demonstrated.

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