Robotic swimmer/pump based on an optimal wave generating mechanism

Setter, Eyal; Bucher, Izhak

doi:10.1016/j.mechmachtheory.2013.07.017

Cited by 5 publications

(3 citation statements)

References 20 publications

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“…Choosing a frequency that would generate a wavenumber with k = 2p × 3:75, one can plot equation (8), as shown in Figure 2. Evidently, equation 8is far more complex than equation (5) and it fails to describe the nature of the propagating phenomenon. In order to capture such phenomena experimentally, special methods are required.…”

Section: Background and Motivationmentioning

confidence: 99%

“…Identification and optimization of travelling waves vibrations are required in application such as ultrasonic motors [2], near field acoustic levitation and transportation motors [3,4] and low Reynolds number swimmers [5]. In recent years the characteristics of periodic structures and cellular materials is of great interest, especially in light of the metamaterial concept [6].…”

Section: Introductionmentioning

confidence: 99%

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Experimental travelling waves identification in mechanical structures

Bucher

Gabai

Plat

et al. 2017

Mathematics and Mechanics of Solids

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Vibrations are often represented as a sum of standing waves in space, i.e. normal modes of vibration. While this can be mathematically accurate, the representation as travelling waves can be compact and more appropriate from a physical point of view, in particular when the energy flux along the structure is meaningful. The quantification of travelling waves assists in computing the energy being transferred and propagated along a structure. It can provide local as well as global information about the structure through which the mechanical energy flows. Presented in this paper is a new method to quantify the fraction of mechanical power being transmitted in a vibration cycle at a specific direction in space using measured data. It is shown that the method can detect local defects causing slight non-uniformity of the energy flux. Equivalence is being made with the electrical power factor and electromagnetic standing waves ratio, commonly employed in such cases. Other methods to perform experiment based wave identification in one-dimension are compared with the power flow based identification. Including a signal processing approach that fits an ellipse to the complex amplitude curve and Hilbert transform for obtaining the local phase and amplitude. A new representation of the active and reactive power flow is developed and its relationship to standing waves ratio is demonstrated analytically and experimentally.

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Section: Background and Motivationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental travelling waves identification in mechanical structures

Bucher

Gabai

Plat

et al. 2017

Mathematics and Mechanics of Solids

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“…A different motivation is provided by the robotic swimmer of Setter, Bucher & Haber (2012); see also Palagi et al (2013) and Setter & Bucher (2013, 2014. This device consists of a tube containing a motor driving wave-like normal surface displacements, and was designed as a cylindrical analogue of Taylor's sheet.…”

Section: Introductionmentioning

confidence: 99%

Slender axisymmetric Stokesian swimmers

Toppaladoddi¹,

Balmforth²

2014

J. Fluid Mech.

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Slender-body theory is used to study axisymmetric swimmers propelled by motions of their surfaces. To leading order, the locomotion speed is given by an integral involving the fluid velocity at the surface of the slender body. Locomotion speeds are calculated for fixed-shape swimmers with prescribed fluid surface velocities and for impermeable swimmers driven by propagating surface waves. Next, the internal mechanics is considered, modelling the swimmer as a viscous fluid bounded by an elastic shell. Prescribed forces are exerted on the shell to drive both the internal and external fluid flow and the surface waves. The internal fluid mechanics is determined using lubrication theory. Locomotion speeds are calculated for transverse and longitudinal waves of surface deformation, and the efficiency of the motions is determined. Transverse surface waves are both weaker and less efficient at driving locomotion than longitudinal waves. The results indicate how estimates of swimming speed based on nearly spherical swimmers with low-amplitude surface waves can be adapted for slender swimmers with nonlinear surface deformations.

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