Intensified flow dynamics by second-order acoustic standing-wave mode: Vortex-excited acoustic resonances in channel branches

2019 ◽  
Vol 31 (3) ◽  
pp. 035105 ◽  
Keyword(s):  
Standing Wave ◽  
Wave Mode ◽  
Second Order ◽  
Flow Dynamics ◽  
Acoustic Standing Wave ◽  
Acoustic Resonances

scholarly journals Outer Acoustic Streaming Flow Driven by Asymmetric Acoustic Resonances

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 65
Author(s):  
Junjun Lei ◽  
Gaokun Zheng ◽  
Zhen Yao ◽  
Zhigang Huang
Keyword(s):  
Standing Wave ◽  
Slip Velocity ◽  
Acoustic Pressure ◽  
Acoustic Radiation ◽  
Acoustic Streaming ◽  
Acoustic Standing Wave ◽  
Acoustic Resonances ◽  
Streaming Flows ◽  
Limiting Velocity ◽  
Streaming Flow

While boundary-driven acoustic streaming resulting from the interaction of sound, fluids and walls in symmetric acoustic resonances have been intensively studied in the literature, the acoustic streaming fields driven by asymmetric acoustic resonances remain largely unexplored. Here, we present a theoretical and numerical analysis of outer acoustic streaming flows generated over a fluid–solid interface above which a symmetric or asymmetric acoustic standing wave is established. The asymmetric standing wave is defined by a shift of acoustic pressure in its magnitude, i.e., S0, and the resulting outer acoustic streaming is analyzed using the limiting velocity method. We show that, in symmetric acoustic resonances (S0 = 0), on a slip-velocity boundary, the limiting velocities always drive fluids from the acoustic pressure node towards adjacent antinodes. In confined geometry where a slip-velocity condition is applied to two parallel walls, the characteristics of the obtained outer acoustic streaming replicates that of Rayleigh streaming. In an asymmetric standing wave where S0 ≠ 0, however, it is found that the resulting limiting velocity node (i.e., the dividing point of limiting velocities) on the slip-velocity boundary locates at a different position to acoustic pressure node and, more importantly, is shown to be independent of S0, enabling spatial separation of acoustic radiation force and acoustic streaming flows. The results show the richness of boundary-driven acoustic streaming pattern variations that arise in standing wave fields and have potentials in many microfluidics applications such as acoustic streaming flow control and particle manipulation.

scholarly journals Analysis of the effects of acoustic levitation to simulate the microgravity environment on the development of early zebrafish embryos

RSC Advances ◽  
2020 ◽  
Vol 10 (72) ◽  
pp. 44593-44600
Author(s):  
Li Li ◽  
Ning Gu ◽  
Huijuan Dong ◽  
Bingsheng Li ◽  
Kenneth T. V. G.
Keyword(s):  
Wave Field ◽  
Standing Wave ◽  
Development Stage ◽  
Microgravity Environment ◽  
Acoustic Levitation ◽  
Zebrafish Embryos ◽  
Acoustic Standing Wave ◽  
Standing Wave Field

Influence of acoustic standing wave field creating acoustic levitation, on each development stage of early zebrafish embryos has been studied.

Effect of the Separation Distance on the Aeroacoustic Source of Multiple Shallow Cavities

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Ayman A. Shaaban ◽  
Samir Ziada
Keyword(s):  
Standing Wave ◽  
Separation Distance ◽  
Destructive Interference ◽  
Acoustic Standing Wave ◽  
Separation Ratio ◽  
Sound Levels ◽  
Standing Wave Method ◽  
Image Velocimetry ◽  
Strong Source ◽  
Shallow Cavities

Flow over ducted shallow cavities can excite fluid resonant oscillations. A common industrial application is the flow in corrugated pipes that can be modeled as a series of consecutive shallow cavities. In the current study, the effect of the separation distance on the aeroacoustic source of multiple shallow cavities is investigated. The standing wave method (SWM) is used to measure the source, where multiple microphones reconstruct the acoustic standing wave upstream and downstream of the cavities. The effect of the ratio between the separation distance to cavity length is investigated for a practical range from 0.5 to 1.375 for two- and three-cavity configurations. At low and intermediate sound levels, constructive hydrodynamic interference, resulting in a strong source, is observed for the extremum spacing ratios of 0.5 and 1.375. However, at high excitation levels, 10% and higher, the source, slightly but consistently, decreases upon increasing the separation ratio. These trends persist for both the double- and triple-cavity configurations. On the other hand, the separation distance of destructive interference is found to depend on the number of cavities of the tested configuration. Particle image velocimetry (PIV) measurements of the constructive interference cases show strong synchronized vorticity shedding in all cavities. Each cavity contribution to the total aeroacoustic source is then examined by means of Howe's analogy, and the percentage contribution of each cavity is found to depend on the excitation level.

Agglomerate fragmentation in high-intensity acoustic standing wave fields

2016 ◽  
Vol 291 ◽  
pp. 214-222 ◽  
Author(s):  
Claas Knoop ◽  
Zinaida Todorova ◽  
Jürgen Tomas ◽  
Udo Fritsching
Keyword(s):  
Standing Wave ◽  
High Intensity ◽  
Wave Fields ◽  
Acoustic Standing Wave
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