Bulk‐wave generation due to the nonlinear interaction of surface acoustic waves

1978 ◽  
Vol 49 (12) ◽  
pp. 5924-5927 ◽  
Author(s):  
Yasuhiko Nakagawa ◽  
Tadahiko Dobashi ◽  
Yoshihiko Saigusa
Keyword(s):  
Nonlinear Interaction ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Wave Generation ◽  
Bulk Wave

Full Band-Gap Silicon Phononic Crystals for Surface Acoustic Waves

2006 ◽  
Author(s):  
Saeed Mohammadi ◽  
Abdelkrim Khelif ◽  
Ryan Westafer ◽  
Eric Massey ◽  
William D. Hunt ◽  
...  
Keyword(s):  
Band Gap ◽  
Acoustic Waves ◽  
Phononic Crystal ◽  
Surface Acoustic Waves ◽  
Hexagonal Lattice ◽  
Phononic Crystals ◽  
Bulk Wave ◽  
Filling Fraction ◽  
Phononic Band Gap ◽  
Wide Range

Periodic elastic structures, called phononic crystals, show interesting frequency domain characteristics that can greatly influence the performance of acoustic and ultrasonic devices for several applications. Phononic crystals are acoustic counterparts of the extensively-investigated photonic crystals that are made by varying material properties periodically. Here we demonstrate the existence of phononic band-gaps for surface acoustic waves (SAWs) in a half-space of two dimensional phononic crystals consisting of hexagonal (honeycomb) arrangement of air cylinders in a crystalline Silicon background with low filling fraction. A theoretical calculation of band structure for bulk wave using finite element method is also achieved and shows that there is no complete phononic band gap in the case of the low filling fraction. Fabrication of the holes in Silicon is done by optical lithography and deep Silicon dry etching. In the experimental characterization, we have used slanted finger interdigitated transducers deposited on a thin layer of Zinc oxide (sputtered on top of the phononic crystal structure to excite elastic surface waves in Silicon) to cover a wide range of frequencies. We believe this to be the first reported demonstration of phononic band-gap for SAWs in a hexagonal lattice phononic crystal at such a high frequency.

Nonlinear interaction between surface acoustic waves and electrons in GaAs resonant-tunneling structures

2000 ◽  
Vol 62 (11) ◽  
pp. 6948-6951 ◽  
Author(s):  
A. B. Hutchinson ◽  
V. I. Talyanskii ◽  
M. Pepper ◽  
G. Gumbs ◽  
G. R. Aǐzin ◽  
...  
Keyword(s):  
Nonlinear Interaction ◽  
Acoustic Waves ◽  
Resonant Tunneling ◽  
Surface Acoustic Waves

scholarly journals On the influence of viscosity and caustics on acoustic streaming in sessile droplets: an experimental and a numerical study with a cost-effective method

2017 ◽  
Vol 821 ◽  
pp. 384-420 ◽  
Author(s):  
A. Riaud ◽  
M. Baudoin ◽  
O. Bou Matar ◽  
J.-L. Thomas ◽  
P. Brunet
Keyword(s):  
Numerical Method ◽  
Flow Structure ◽  
Acoustic Waves ◽  
Wave Attenuation ◽  
Numerical Study ◽  
Surface Acoustic Waves ◽  
Acoustic Streaming ◽  
Fluid Viscosity ◽  
Bulk Wave ◽  
Dimensionless Numbers

When an acoustic wave travels in a lossy medium such as a liquid, it progressively transfers its pseudo-momentum to the fluid, which results in a steady flow called acoustic streaming. This phenomenon involves a balance between sound attenuation and shear, such that the streaming flow does not vanish in the limit of vanishing viscosity. Hence, the effect of viscosity has long been ignored in acoustic streaming experiments. Here, we investigate the acoustic streaming in sessile droplets exposed to surface acoustic waves. According to experimental data, the flow structure and velocity magnitude are both strongly influenced by the fluid viscosity. We compute the sound wave propagation and hydrodynamic flow motion using a numerical method that reduces memory requirements via a spatial filtering of the acoustic streaming momentum source terms. These calculations agree qualitatively well with experiments and reveal how the acoustic field in the droplet, which is dominated by a few caustics, controls the flow pattern. We evidence that chaotic acoustic fields in droplets are dominated by a few caustics. It appears that the caustics drive the flow, which allows for qualitative prediction of the flow structure. Finally, we apply our numerical method to a broader span of fluids and frequencies. We show that the canonical case of the acoustic streaming in a hemispherical sessile droplet resting on a lithium niobate substrate only depends on two dimensionless numbers related to the surface and bulk wave attenuation. Even in such a baseline configuration, we observe and characterize four distinct flow regimes.

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