Avoided crossings in three coupled oscillators as a model system of acoustic bubbles
三个声耦合气泡的共振频率和振荡相位的检查,以表明避免交叉可以出现在一个多气泡系统。通过一个简单的耦合振子模型,我们表明,如果至少有三个气泡存在,它是可能的,它们的共振频率作为气泡之间的分离距离的函数,以避免交叉。通过对振荡相位的研究,并在对跃迁频率分析的基础上,提出了一种新的振荡相位分析方法[M. Ida,Phys. Lett. A 297,210(2002); M. Ida,J. Phys. Soc. Jpn. 71,1214(2002)]的耦合气泡,我们表明,一个独特的状态交换发生在避免交叉区域中的一个点的气泡之间,在那里的三重气泡系统的共振频率与过渡频率不对应的共振频率交叉。
Alternative interpretation of the sign reversal of secondary Bjerknes force acting between two pulsating gas bubbles
已知在特定情况下,作为作用在脉动气泡之间的辐射力的次级Bjerknes力改变,例如,从吸引到排斥。本文对两个球形气泡的这种现象进行了理论讨论。本文基于对相互作用气泡跃迁频率的分析[M. Ida,Phys. Lett. A 297,210(2002)]提供了一种解释,与以前的解释不同(例如,Doinikov和Zavtrak [Phys.Fluids 7,1923(1995)])。它示出,例如,反转时发生的一个气泡是较小的,另一个是大于共振尺寸是由于第二高的过渡频率的较小的气泡,这是不能使用传统的自然频率分析。
The dynamics of hydrogen bubbles produced by water electrolysis in an acidic electrolyte are studied using electrochemical and optical methods. A defined cyclic modulation of the electric potential is applied at a microelectrode to produce pairs of interacting H$_2$ bubbles in a controlled manner. Three scenarios of interactions are identified and systematically studied. The most prominent one consists in a sudden reversal in the motion of the first detached bubble, its return to the electrode and finally its coalescence with the second bubble. Attested by Toepler's schlieren technique, an exp…
Acoustic microstreaming due to an oscillating microbubble is analytically investigated to obtain the circular streaming motion adjacent to a nearby wall. Classical theory due to Nyborg is carefully derived in the radial coordinates. The theory is used to obtain the flow field and the vortical motion caused by the microbubble motion. The length of the vertices are decreasing when the microbubble is excited at distances close to the rigid wall, while the maximum shear stress is increasing.
Most of the current applications of acoustic cavitation use bubble clusters that exhibit multibubble dynamics. This necessitates a complete understanding of the mutual nonlinear coupling between individual bubbles. In this study, strong nonlinear coupling is investigated in bubble pairs which is the simplest case of a bubble-cluster. This leads to the derivation of a more comprehensive set of coupled Keller-Miksis equations (KMEs) that contain nonlinear coupling terms of higher order. The governing KMEs take into account the convective contribution that stems from the Navier-Stokes equation. T…
Oblique collision of solid particles with surfaces has been a topic of extensive study in Newtonian mechanics, which also explains the motion of bubbles and droplets to some extent. Here, we observe that air bubbles exhibit a backflipping behavior when they collide with a tilted surface. Our experiments reveal that bubbles with radii 0.6-0.7 mm undergo backflipping when they collide with surfaces at an angle of up to 15^o with the strongest backflipping at 3^o. Particle image velocimetry reveals that the backflipping behavior is caused by wake-induced circulation around the bubble, which appli…
Nonlinear optical processes are vital for fields including telecommunications, signal processing, data storage, spectroscopy, sensing, and imaging. As an independent research area, nonlinear optics began with the invention of the laser, because practical sources of intense light needed to generate optical nonlinearities were not previously available. However the high power requirements of many nonlinear optical systems limit their use, especially in portable or medical applications, and so there is a push to develop new materials and resonant structures capable of producing nonlinear optical p…