Transition to Traveling Waves from Standing Waves in a Rectangular Container Subjected to Horizontal Excitations

1997 ◽  
Vol 79 (3) ◽  
pp. 415-418 ◽  
Author(s):  
Z. C. Feng
Keyword(s):  
Traveling Waves ◽  
Standing Waves ◽  
Rectangular Container

The two-sided lid-driven cavity: experiments on stationary and time-dependent flows

2002 ◽  
Vol 450 ◽  
pp. 67-95 ◽  
Author(s):  
CH. BLOHM ◽  
H. C. KUHLMANN
Keyword(s):  
Three Dimensional ◽  
Standing Waves ◽  
Reynolds Numbers ◽  
Time Dependent ◽  
Flow State ◽  
Incompressible Fluid Flow ◽  
Velocity Measurements ◽  
Driven Cavity ◽  
Rectangular Container ◽  
Hot Film

The incompressible fluid flow in a rectangular container driven by two facing sidewalls which move steadily in anti-parallel directions is investigated experimentally for Reynolds numbers up to 1200. The moving sidewalls are realized by two rotating cylinders of large radii tightly closing the cavity. The distance between the moving walls relative to the height of the cavity (aspect ratio) is Γ = 1.96. Laser-Doppler and hot-film techniques are employed to measure steady and time-dependent vortex flows. Beyond a first threshold robust, steady, three-dimensional cells bifurcate supercritically out of the basic flow state. Through a further instability the cellular flow becomes unstable to oscillations in the form of standing waves with the same wavelength as the underlying cellular flow. If both sidewalls move with the same velocity (symmetrical driving), the oscillatory instability is found to be tricritical. The dependence on two sidewall Reynolds numbers of the ranges of existence of steady and oscillatory cellular flows is explored. Flow symmetries and quantitative velocity measurements are presented for representative cases.

scholarly journals Traveling and standing waves mediate pattern formation in cellular protrusions

2020 ◽  
Vol 6 (32) ◽  
pp. eaay7682
Author(s):  
Sayak Bhattacharya ◽  
Tatsat Banerjee ◽  
Yuchuan Miao ◽  
Huiwang Zhan ◽  
Peter N. Devreotes ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Traveling Waves ◽  
Standing Waves ◽  
Cell Cortex ◽  
Theoretical Studies ◽  
Direct Transformation ◽  
Diffusion Parameters ◽  
Excitable Systems ◽  
Mutant Strains ◽  
The Stability

The mechanisms regulating protrusions during amoeboid migration exhibit excitability. Theoretical studies have suggested the possible coexistence of traveling and standing waves in excitable systems. Here, we demonstrate the direct transformation of a traveling into a standing wave and establish conditions for the stability of this conversion. This theory combines excitable wave stopping and the emergence of a family of standing waves at zero velocity, without altering diffusion parameters. Experimentally, we show the existence of this phenomenon on the cell cortex of some Dictyostelium and mammalian mutant strains. We further predict a template that encompasses a spectrum of protrusive phenotypes, including pseudopodia and filopodia, through transitions between traveling and standing waves, allowing the cell to switch between excitability and bistability. Overall, this suggests that a previously-unidentified method of pattern formation, in which traveling waves spread, stop, and turn into standing waves that rearrange to form stable patterns, governs cell motility.

Nonlinear Periodic Systems: Bands and Localization

2009 ◽  
Author(s):  
Alexander Vakakis
Keyword(s):  
Traveling Waves ◽  
Multiple Scales ◽  
Initial Conditions ◽  
Near Field ◽  
Standing Waves ◽  
Nonlinear Resonance ◽  
Nonlinear Effects ◽  
Periodic Media ◽  
Spatially Extended ◽  
Nonlinear Standing Waves

We consider the dynamics of nonlinear mono-coupled periodic media. When coupling dominates over nonlinearity near-field standing waves and spatially extended traveling waves exist, inside stop and pass bands, respectively, of the nonlinear system. Nonlinear standing waves are analytically studied using a nonlinear normal mode formulation, whereas nonlinear traveling waves are analyzed by the method of multiple scales. When the nonlinear effects are of the same order with the coupling ones a completely different picture emerges, since nonlinear resonance interactions are unavoidable. As a result, infinite families of strongly and weakly localized nonlinear standing waves appear with frequencies lying in pass or stop bands of the corresponding linear periodic medium. Moreover, in the limit of weak coupling these solutions develop sensitive dependence on initial conditions, and the possibility of spatial chaos in the system exists. Some additional results on chaotic dynamics in linear periodic media with strongly nonlinear disorders are reviewed.

scholarly journals Standing waves and traveling waves in visual cortex

2010 ◽  
Vol 6 (13) ◽  
pp. 25-25
Author(s):  
M. Carandini ◽  
R. A. Frazor ◽  
A. Benucci
Keyword(s):  
Visual Cortex ◽  
Traveling Waves ◽  
Standing Waves

scholarly journals Comparative Study of Traveling and Standing Wave-Based Locomotion of Legged Bidirectional Miniature Piezoelectric Robots

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 171
Author(s):  
Jorge Hernando-García ◽  
Jose Luis García-Caraballo ◽  
Víctor Ruiz-Díez ◽  
Jose Luis Sánchez-Rojas
Keyword(s):  
Traveling Waves ◽  
Vibration Mode ◽  
Glass Plate ◽  
Excitation Frequency ◽  
Standing Waves ◽  
Flexural Vibration ◽  
Precise Location ◽  
Modes Of Vibration ◽  
3D Printed ◽  
Locomotion Speed

The use of wave-based locomotion mechanisms is already well established in the field of robotics, using either standing waves (SW) or traveling waves (TW). The motivation of this work was to compare both the SW- and the TW-based motion of a 20-mm long sub-gram glass plate, with attached 3D printed legs, and piezoelectric patches for the actuation. The fabrication of the robot did not require sophisticated techniques and the speed of motion was measured under different loading conditions. In the case of the TW mechanism, the influence of using different pairs of modes to generate the TW on the locomotion speed has been studied, as well as the effect of the coupling of the TW motion and the first flexural vibration mode of the legs. This analysis resulted in a maximum unloaded speed of 6 bodylengths/s (BL/s) at 65 V peak-to-peak (Vpp). The SW approach also examined different modes of vibration and a speed of locomotion as high as 14 BL/s was achieved, requiring, unlike the TW case, a highly precise location of the legs on the glass supporting platform and a precise tuning of the excitation frequency.

scholarly journals Standing Waves and Traveling Waves Distinguish Two Circuits in Visual Cortex

Neuron ◽  
2007 ◽  
Vol 55 (1) ◽  
pp. 103-117 ◽  
Author(s):  
Andrea Benucci ◽  
Robert A. Frazor ◽  
Matteo Carandini
Keyword(s):  
Visual Cortex ◽  
Traveling Waves ◽  
Standing Waves

Noncontact Manipulation of Light Objects Based on Parameter Modulations of Acoustic Pressure Nodes

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Joong-kyoo Park ◽  
Paul I. Ro
Keyword(s):  
Long Range ◽  
Standing Wave ◽  
Traveling Waves ◽  
Phase Modulation ◽  
Acoustic Pressure ◽  
Standing Waves ◽  
Acoustic Levitation

An investigation of noncontact manipulation techniques based on acoustic levitation was undertaken in air. The standing wave acoustic levitation (SWAL) was observed when standing waves trap small objects at pressure nodes. In this paper, two ultrasonic bolt-clamped Langevin type transducers (BLTs) generating traveling waves by modulating parameters of the two traveling waves were used to manipulate a trapped object. Frequency, amplitude, and phase modulations of the two actuators were exploited. From simulation and experiments, the phase modulation was prominent among other methods due to its long range and smooth operation. It is also found that angles between two actuators affect the trajectory of the trapped object during the parameter modulations. Sinusoidal and elliptic paths of the object were observed experimentally through a combination of parameters at certain tilt angles.

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