Interfacial Jetting Phenomena Induced by Focused Surface Vibrations

Tan, Ming K.; Friend, James; Yeo, Leslie

doi:10.1103/physrevlett.103.024501

Cited by 187 publications

(161 citation statements)

References 14 publications

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“…This shows that for our SAW system we have turbulent acoustic streaming in all cases, with the 0.74 nm amplitude case near the critical amplitude, if we assume throughout that the amplitude of the acoustic wave is of the same order of magnitude as the amplitude of the SAW the drop resides on, an assumption that we have found to be valid elsewhere. 59 The matter of turbulent acoustic streaming is important because it is key to explaining how very high frequency acoustic excitation can result in such low-frequency acoustic capillary waves, especially when there is no known mechanism to drive a subharmonic cascade in the capillary waves themselves. Unlike the capillary wave phenomena, a large-scale subharmonic cascade is possible in a turbulent jet, 55,56,58 and this appears to underlie the driving of low-frequency capillary waves by the very high frequency boundary vibration.…”

Section: ■ Resultsmentioning

confidence: 99%

Microscale Capillary Wave Turbulence Excited by High Frequency Vibration

Blamey

Yeo²,

Friend

2013

Langmuir

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Low frequency (O(10 Hz−10 kHz)) vibration excitation of capillary waves has been extensively studied for nearly two centuries. Such waves appear at the excitation frequency or at rational multiples of the excitation frequency through nonlinear coupling as a result of the finite displacement of the wave, most often at one-half the excitation frequency in so-called Faraday waves and twice this frequency in superharmonic waves. Less understood, however, are the dynamics of capillary waves driven by high-frequency vibration (>O(100 kHz)) and small interface length scales, an arrangement ideal for a broad variety of applications, from nebulizers for pulmonary drug delivery to complex nanoparticle synthesis. In the few studies conducted to date, a marked departure from the predictions of classical Faraday wave theory has been shown, with the appearance of broadband capillary wave generation from 100 Hz to the excitation frequency and beyond, without a clear explanation. We show that weak wave turbulence is the dominant mechanism in the behavior of the system, as evident from wave height frequency spectra that closely follow the Rayleigh−Jeans spectral response η ≈ ω −17/12 as a consequence of a period-halving, weakly turbulent cascade that appears within a 1 mm water drop whether driven by thickness-mode or surface acoustic Rayleigh wave excitation. However, such a cascade is one-way, from low to high frequencies. The mechanism of exciting the cascade with high-frequency acoustic waves is an acoustic streaming-driven turbulent jet in the fluid bulk, driving the fundamental capillary wave resonance through the well-known coupling between bulk flow and surface waves. Unlike capillary waves, turbulent acoustic streaming can exhibit subharmonic cascades from high to low frequencies; here it appears from the excitation frequency all the way to the fundamental modes of the capillary wave at some four orders of magnitude in frequency less than the excitation frequency, enabling the capillary weakly turbulent wave cascade to form from the fundamental capillary wave upward.

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Section: ■ Resultsmentioning

confidence: 99%

Microscale Capillary Wave Turbulence Excited by High Frequency Vibration

Blamey

Yeo²,

Friend

2013

Langmuir

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“…17 Both an inclined angle jetting along the Rayleigh angle using one-side interdigitated transducers (IDTs) 18 and a nearly vertical jetting based on a standing Rayleigh SAW generated from two opposite focusing IDTs 19 have been reported. However, as far as we know, there are no reports on the jetting phenomena induced from the SH-SAW devices.…”

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confidence: 99%

Vertical jetting induced by shear horizontal leaky surface acoustic wave on 36° Y-X LiTaO3

Quan

Luo

et al. 2017

Applied Physics Letters

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Shear horizontal surface acoustic waves (SH-SAWs) have been regarded as good candidates for liquid sensing applications but are inefficient in fluid manipulation due to a minimal fluid coupling between the fluid and acoustic waves. However, in this letter, a vertical jetting function was realized using the SH-SAW generated from a 36° Y-X LiTaO3 SAW device. The jetting of the droplet induced by the SH-SAWs was observed nearly along the vertical direction, and the aspect ratio of the liquid beam is proportional to the applied power before breaking up, which is dramatically different from those generated from the conventional Rayleigh SAWs. By conducting theoretical simulation and experimental investigation on the SH-SAWs systematically, we concluded that the wave/energy pressure dissipated into the sessile droplets causes this vertical ejection on the device surface.

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“…Similarly, the interaction of sound waves and vibrations with fluids has an equally rich history dating back to Faraday's 11 observation of capillary waves on vertically vibrated substrates and Rayleigh's 12 description of acoustic streaming in air-filled resonant tubes. It has, however, only been in the last decade that renewed interest has emerged in the subject, particularly surrounding flows arising from nanometer amplitude highfrequency (MHz order) substrate vibration in the form of surface acoustic waves (SAWs) 13 , not only because of their tremendous potential for driving a variety of microfluidic operations such as drop transport 14 , fluid mixing 15 and particle/ cell alignment 16 , but also because of the recent discovery of associated phenomena such as dynamic colloidal patterning 17 and interfacial jetting 18 . Here we report on a novel collection of dynamic spreading and flow-instability phenomena that arise when a sessile fluid drop is subjected to the SAW.…”

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Unique fingering instabilities and soliton-like wave propagation in thin acoustowetting films

et al. 2012

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Acoustic-fluid interactions not only has had a long history but has recently experienced renewed scrutiny because of their vast potential for microscale fluid and particle manipulation. Here we unravel a fascinating and anomalous ensemble of dynamic 'acoustowetting' phenomena in which a thin film drawn from a sessile drop first spreads in opposition to the acoustic wave propagation direction. The advancing film front then exhibits fingering instabilities akin to classical viscous fingering, but arising through a different and novel mechanism: transverse Fresnel diffraction of the underlying acoustic wave. Peculiar 'solitonlike' wave pulses are observed to grow above these fingers, which, on reaching a critical size, translate away along the wave propagation direction. By elucidating the complex hydrodynamics underpinning the spreading, and associated flow reversal and instability phenomena, we offer insight into the possibility of acoustically controlling fast and uniform film spreading, constituting a flexible and powerful alternative for microfluidic transport.

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Interfacial Jetting Phenomena Induced by Focused Surface Vibrations

Cited by 187 publications

References 14 publications

Microscale Capillary Wave Turbulence Excited by High Frequency Vibration

Microscale Capillary Wave Turbulence Excited by High Frequency Vibration

Vertical jetting induced by shear horizontal leaky surface acoustic wave on 36° Y-X LiTaO3

Unique fingering instabilities and soliton-like wave propagation in thin acoustowetting films

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