Flowfield measurements in the wake of a robotic lamprey

Hultmark, Marcus; Leftwich, Megan C.; Smits, Alexander J.

doi:10.1007/s00348-007-0412-1

Cited by 58 publications

(21 citation statements)

References 8 publications

(17 reference statements)

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“…In the apparatus, the robotic fish is mounted on a servo guide rail system and the towing speed is not preset but determined by the measured force acting on the body of the fish. Some previous studies have investigated hydrodynamics by using robots, but most of the robotic models did not satisfy selfpropelled conditions [4,19]. Encouraged by the potential generality of this simultaneous measurement method based on a force-feedback technique, we believe that unsteady biofluid dynamic experiments can be conducted using the present method, in such areas as the robotic undulatory fin [47,48], pulsed jet propulsion [49], or other biomimetic devices [50].…”

Section: Investigating Fish Biomechanics With Self-propelled Robotsmentioning

confidence: 99%

Hydrodynamic investigation of a self-propelled robotic fish based on a force-feedback control method

Wen

Wang

et al. 2012

Bioinspir. Biomim.

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We implement a mackerel (Scomber scombrus) body-shaped robot, programmed to display the three most typical body/caudal fin undulatory kinematics (i.e. anguilliform, carangiform and thunniform), in order to biomimetically investigate hydrodynamic issues not easily tackled experimentally with live fish. The robotic mackerel, mounted on a servo towing system and initially at rest, can determine its self-propelled speed by measuring the external force acting upon it and allowing for the simultaneous measurement of power, flow field and self-propelled speed. Experimental results showed that the robotic swimmer with thunniform kinematics achieved a faster final swimming speed (St = 0.424) relative to those with carangiform (St = 0.43) and anguilliform kinematics (St = 0.55). The thrust efficiency, estimated from a digital particle image velocimetry (DPIV) flow field, showed that the robotic swimmer with thunniform kinematics is more efficient (47.3%) than those with carangiform (31.4%) and anguilliform kinematics (26.6%). Furthermore, the DPIV measurements illustrate that the large-scale characteristics of the flow pattern generated by the robotic swimmer with both anguilliform and carangiform kinematics were wedge-like, double-row wake structures. Additionally, a typical single-row reverse Karman vortex was produced by the robotic swimmer using thunniform kinematics. Finally, we discuss this novel force-feedback-controlled experimental method, and review the relative self-propelled hydrodynamic results of the robot when utilizing the three types of undulatory kinematics.

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Section: Investigating Fish Biomechanics With Self-propelled Robotsmentioning

confidence: 99%

Hydrodynamic investigation of a self-propelled robotic fish based on a force-feedback control method

Wen

Wang

et al. 2012

Bioinspir. Biomim.

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“…[15], Tytell and Lauder [16] and Hultmark et al . [17]). Fish and Lauder [18] have indicated that the wake structure is different between eel-like (anguilliform) fishes and fishes with a narrow tail peduncle region ( e .…”

Section: Introductionmentioning

confidence: 99%

Numerical study on the hydrodynamics of thunniform bio-inspired swimming under self-propulsion

Liu

2017

PLoS ONE

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Numerical simulations are employed to study the hydrodynamics of self-propelled thunniform swimming. The swimmer is modeled as a tuna-like flexible body undulating with kinematics of thunniform type. The wake evolution follows the vortex structures arranged nearly vertical to the forward direction, vortex dipole formation resulting in the propulsion motion, and finally a reverse Kármán vortex street. We also carry out a systematic parametric study of various aspects of the fluid dynamics behind the freely swimming behavior, including the swimming speed, hydrodynamic forces, power requirement and wake vortices. The present results show that the fin thrust as well as swimming velocity is an increasing function of both tail undulating amplitude Ap and oscillating amplitude of the caudal fin θm. Whereas change on the propulsive performance with Ap is associated with the strength of wake vortices and the area of suction region on the fin, the swimming performance improves with θm due to the favorable tilting of the fin that make the pressure difference force more oriented toward the thrust direction. Moreover, the energy loss in the transverse direction and the power requirement increase with Ap but decrease with θm, and this indicates that for achieving a desired swimming speed increasing θm seems more efficiently than increasing Ap. Furthermore, we have compared the current simulations with the published experimental studies on undulatory swimming. Comparisons show that our work tackles the flow regime of natural thunniform swimmers and follows the principal scaling law of undulatory locomotion reported. Finally, this study enables a detailed quantitative analysis, which is difficult to obtain by experiments, of the force production of the thunniform mode as well as its connection to the self-propelled swimming kinematics and vortex wake structure. The current findings help provide insights into the swimming performance and mechanisms of self-propelled thunniform locomotion.

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“…In these studies, the imposed kinematics were quantified using a midline displacement function h(x,t) = a(x) sin(kx − ωt), which describes a traveling wave with spatially dependent wave amplitude a(x) and wave speed c = ω/k, where x is the position along the length of the fish, head to tail, k is the wave number (reciprocal of wavelength), and ω is the oscillation frequency. In the anguilliform case, a(x) was fit to an exponential function matching the data from Tytell and Lauder [21] based on American eels, and the wave number k was set based on the value used for a robotic lamprey [4]. In the carangiform case, the wave amplitude a(x) was expressed as a quadratic fit to the amplitude observations of Videler and Hess [15], with a wavelength based on studies by Videler and Wardle [22].…”

Section: Background On Fish Kinematicsmentioning

confidence: 99%

“…A greater understanding of their movement allows for better appreciation of fish themselves, as well as * Address all correspondence to this author valuable insight to a very efficient form of underwater locomotion. The work in this area can also be applied to the development of modern technology, as today there is a lot of interest in biomimetic robotic fish [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Complex Modal Analysis of the Swimming Motion of a Whiting

Feeny

2011

Volume 1: 23rd Biennial Conference on Mechanical Vibration and Noise, Parts a and B

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The kinematics of the transverse motion of a swimming fish are analyzed using a complex modal decomposition. Cinematographic images of a swimming whiting (Gadus merlangus) were obtained from the work of Sir James Gray (Journal of Experimental Biology, 1933). The position of the midline for each image was determined, and used to produce planar positions of virtual markers distributed along the midline of the fish. Transverse deflections of each virtual marker were used for the complex orthogonal decomposition of modes. This method was applied to a normal whiting and an amputated whiting, both of Gray’s paper. The fish motions were well represented by a single complex mode, which was used as a modal filter. The modal coordinate was also extracted. The mode and modal coordinate were used to estimate the frequency, wavelength, and wave speed. The amputated fish was compared to the non-amputated fish, and the different amount of traveling in the respective waveforms was quantified.

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Flowfield measurements in the wake of a robotic lamprey

Cited by 58 publications

References 8 publications

Hydrodynamic investigation of a self-propelled robotic fish based on a force-feedback control method

Hydrodynamic investigation of a self-propelled robotic fish based on a force-feedback control method

Numerical study on the hydrodynamics of thunniform bio-inspired swimming under self-propulsion

Complex Modal Analysis of the Swimming Motion of a Whiting

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