scholarly journals Acoustic radiation forces at liquid interfaces impact the performance of acoustophoresis

Lab on a Chip ◽  
2014 ◽  
Vol 14 (17) ◽  
pp. 3394-3400 ◽  
Author(s):  
Sameer Deshmukh ◽  
Zbigniew Brzozka ◽  
Thomas Laurell ◽  
Per Augustsson
Keyword(s):  
Acoustic Field ◽  
Speed Of Sound ◽  
Acoustic Radiation ◽  
Liquid Interfaces ◽  
Radiation Forces

Flow laminated liquids can relocate in a resonant acoustic field due to differences in density and speed of sound.

scholarly journals Numerical Analysis of Structure Acoustic Radiation Based on Wave Superposition Method

2011 ◽  
Vol 2-3 ◽  
pp. 733-738
Author(s):  
Sheng Yao Gao ◽  
De Shi Wang ◽  
Yi Qun Du
Keyword(s):  
Integral Equation ◽  
Acoustic Field ◽  
Acoustic Radiation ◽  
Boundary Surface ◽  
Impact Factors ◽  
Power Calculation ◽  
Superposition Method ◽  
Sound Power ◽  
Wave Superposition ◽  
Equivalent Sources

To overcome the non-uniqueness of solution at eigenfrequencies in the boundary integral equation method for structural acoustic radiation, wave superposition method is introduced to study the acoustics characteristics including acoustic field reconstruction and sound power calculation. The numerical method is implemented by using the acoustic field from a series of virtual sources which are collocated near the boundary surface to replace the acoustic field of the radiator, namely the principle of equivalent. How to collocate these equivalent sources is not indicated definitely. Once wave superposition method is applied to sound power calculation, it is necessary to evaluate its accuracy and impact factors. In the paper, the basic principle of wave superposition method is described, and then the integral equation is discretized. Also, the impact factors including element numbers, frequency limitation, and distance between virtual source and integral surface are analyzed in the process of calculate the acoustic radiation from the simply supported thin plate under concentrated force. The extensive measures of acoustic field at the thin plate are compared with results obtain using different numerical methods. The results show that: (a) The agreement between the results from the above numerical methods is excellent. The wave superposition method requires fewer elements and hence is faster. But the extensive numerical modeling suggests that as long as the volume velocity matching yields more than adequate accuracy. (b) The equivalent sources should be collocated inside the radiator. And the accuracy of a given Gauss integration formula will decrease as the source approaches the boundary surface. (c) The numerical method is applicable to the acoustic radiation of structure with complicated shape. (d) The method described in this paper can be used to perform effectively sound power calculation, and its application range can be extended on the basis of these conclusions.

scholarly journals A numerical study of microparticle acoustophoresis driven by acoustic radiation forces and streaming-induced drag forces

Lab on a Chip ◽  
2012 ◽  
Vol 12 (22) ◽  
pp. 4617 ◽  
Author(s):  
Peter Barkholt Muller ◽  
Rune Barnkob ◽  
Mads Jakob Herring Jensen ◽  
Henrik Bruus
Keyword(s):  
Acoustic Radiation ◽  
Numerical Study ◽  
Drag Forces ◽  
Induced Drag ◽  
Radiation Forces

scholarly journals Structure-Acoustic Coupling Analysis of Vibration and Underwater Acoustic Radiation of a Ring-Stiffened Conical Shell

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Qingtao Gong ◽  
Zhanyang Chen ◽  
Hongbin Gui ◽  
Dong Yu
Keyword(s):  
Acoustic Field ◽  
Conical Shell ◽  
Sound Pressure ◽  
Field Model ◽  
Acoustic Radiation ◽  
Rear Side ◽  
The Finite Element Method ◽  
Underwater Acoustic ◽  
Acoustic Coupling ◽  
Element Method

The underwater acoustic radiation of the submarine power cabin has recently become a hot topic in the industry and also in the academia. In this article, the vibration and underwater acoustic radiation of a ring-stiffened conical shell with bases are investigated numerically by means of the combination of the finite element method and boundary element method. The acoustic radiation field is obtained by the traditional acoustic field model and ISO acoustic field model, respectively. A series of numerical examples are given, and the results are compared. Besides, the sound pressure at different positions with frequency is further studied. It is shown that the sound radiated by the structure mainly propagates to the side directions of the shell and propagates relatively less to the front side and the rear side.

Effects of Quay Wall and Seabed Reflection on the AUV Acoustic Radiation Test Analysis

2014 ◽  
Vol 599-601 ◽  
pp. 922-926
Author(s):  
Guo Liang Xu ◽  
Qi Wei He ◽  
Shao Chun Ding ◽  
Hai Bo Wan
Keyword(s):  
Acoustic Field ◽  
Field Test ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Near Field ◽  
Test Analysis ◽  
Complex Sound ◽  
Quay Wall ◽  
Radiation Test ◽  
Acoustical Holography

To analyze effects of quay environment on the AUV radiated acoustic field test, the PNAH (PNAH: planar near-field acoustical holography) was used to simulate acoustic field. By simulating the free and non-free acoustic field and comparing amplitudes and angles of complex sound pressure, Analyze effects of quay wall and seabed reflection on the AUV radiated acoustic field test to determine the standard of quay wall and seabed environment which meets testing. The work would provide a certain reference for the AUV radiated acoustic field test.

scholarly journals Statistical Patterns of Transmission Losses of Low-Frequency Sound in Shallow Sea Waveguides with Gaussian and Non-Gaussian Fluctuations

2019 ◽  
Vol 9 (9) ◽  
pp. 1841
Author(s):  
Fengqin Zhu ◽  
Oleg E. Gulin ◽  
Igor O. Yaroshchuk
Keyword(s):  
Acoustic Field ◽  
Speed Of Sound ◽  
Transmission Loss ◽  
Low Frequency ◽  
Local Mode ◽  
Average Intensity ◽  
Slowing Down ◽  
Gaussian Fluctuations ◽  
Mode Method ◽  
Non Gaussian

Based on the local mode method, the problem of the average intensity (transmission loss) behavior in shallow waveguides with losses in the bottom and fluctuations of the speed of sound in water is considered. It was previously shown that the presence in a waveguide with absorbing penetrable bottom of 2D random inhomogeneities of the speed of sound leads to the appearance of strong fluctuations in the acoustic field already at relatively small distances from the sound source. One of the most important and interesting manifestations of this is the slowing down of the average intensity of the acoustic field compared with a waveguide, which has no such random inhomogeneities of the speed of sound. This paper presents the results of a numerical analysis of the decay of the average field intensity in the presence of both Gaussian and non-Gaussian fluctuations in the speed of sound. It is shown that non-Gaussian fluctuations do not fundamentally change the conclusion about reducing losses during the propagation of a sound signal but can enhance this effect.

On generation of sound in wall-bounded shear flows: back action of sound and global acoustic coupling

2011 ◽  
Vol 689 ◽  
pp. 279-316 ◽  
Author(s):  
Xuesong Wu
Keyword(s):  
Acoustic Field ◽  
Acoustic Radiation ◽  
Leading Order ◽  
Mean Flow ◽  
S Wave ◽  
Acoustic Coupling ◽  
Hydrodynamic Motion ◽  
Roughness Elements ◽  
Supersonic Regime ◽  
Back Action

AbstractIn two previous papers (Wu, J. Fluid Mech., vol. 453, 2002, p. 289, and Wu & Hogg, J. Fluid Mech., vol. 550, 2006, p. 307), a formal asymptotic procedure was developed to calculate the sound radiated by unsteady boundary-layer flows that are described by the triple-deck theory. That approach requires lengthy calculations, and so is now improved to construct a simpler composite theory, which retains the capacity of systematically identifying and approximating the relevant sources, but also naturally includes the effect of mean-flow refraction and more importantly the back action of the emitted sound on the source itself. The combined effect of refraction and back action is represented by an ‘impedance coefficient’, and the present analysis yields an analytical expression for this parameter, which was usually introduced on a semi-empirical basis. The expression indicates that for Mach number $M= O(1)$, the mean-flow refraction and back action of the sound have a leading-order effect on the acoustic field within the shallow angles to the streamwise directions. A parametric study suggests that the back effect of sound is actually appreciable in a sizeable portion of the acoustic field for $M\gt 0. 5$, becomes more pronounced, and eventually influences the entire acoustic field in the transonic limit. In the supersonic regime, the acoustic field is characterized by distinctive Mach-wave beams, which exert a leading-order influence on the source. The analysis also indicates that acoustic radiation in the subsonic and supersonic regimes is fundamentally different. In the subsonic regime, the sound is produced by small-wavenumber components of the hydrodynamic motion, and can be characterized by acoustic multipoles, whereas in the supersonic regime, broadband finite-wavenumber components of the hydrodynamic motion contribute and the concept of a multipolar source becomes untenable. The global acoustic feedback loop is investigated using a model consisting of two well-separated roughness elements, in which the sound wave emitted due to the scattering of a Tollmien–Schlichting (T–S) wave by the downstream roughness propagates upstream and impinges on the upstream roughness to regenerate the T–S wave. Numerical calculations suggest that at high Reynolds numbers and for moderate roughness heights, the long-range acoustic coupling may lead to global instability, which is characterized by self-sustained oscillations at discrete frequencies. The dominant peak frequency may jump from one value to another as the Reynolds number or the distance between the roughness elements is varied gradually.

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