Recent Developments for the Nonlinear Distortion of Non-Dispersive Acoustic Waves: Part II: Multidimensional Systems

1979 ◽  
Vol 11 (8) ◽  
pp. 3-12 ◽  
Author(s):  
J.H. Ginsberg
Keyword(s):  
Acoustic Waves ◽  
Nonlinear Distortion ◽  
Multidimensional Systems ◽  
Recent Developments

scholarly journals Geometric-acoustics analysis of singly scattered, nonlinearly evolving waves by circular cylinders

2020 ◽  
Author(s):  
Michael Muhlestein ◽  
Carl Hart
Keyword(s):  
Acoustic Waves ◽  
Nonlinear Distortion ◽  
Nonlinear Evolution ◽  
Scattered Wave ◽  
High Amplitude ◽  
Circular Cylinders ◽  
Ray Theory ◽  
Theoretical Predictions ◽  
Geometric Acoustics ◽  
The Individual

Geometric acoustics, or acoustic ray theory, is used to analyze the scattering of high-amplitude acoustic waves incident upon rigid circular cylinders. Theoretical predictions of the nonlinear evolution of the scattered wave field are provided, as well as measures of the importance of accounting for nonlinearity. An analysis of scattering by many cylinders is also provided, though the effects of multiple scattering are not considered. Provided the characteristic nonlinear distortion length is much larger than a cylinder radius, the nonlinear evolution of the incident wave is shown to be of much greater importance to the overall evolution than the nonlinear evolution of the individual scattered waves.

On cumulative nonlinear acoustic waveform distortions from high-speed jets

2014 ◽  
Vol 749 ◽  
pp. 331-366 ◽  
Author(s):  
W. J. Baars ◽  
C. E. Tinney ◽  
M. S. Wochner ◽  
M. F. Hamilton
Keyword(s):  
Mach Number ◽  
Acoustic Waves ◽  
High Speed ◽  
Scaling Laws ◽  
Nonlinear Distortion ◽  
Practical Interest ◽  
Laboratory Scale ◽  
Potential Core ◽  
Nonlinear Distortions ◽  
Gaussian Source

AbstractA model is proposed for predicting the presence of cumulative nonlinear distortions in the acoustic waveforms produced by high-speed jet flows. The model relies on the conventional definition of the acoustic shock formation distance and employs an effective Gol’dberg number$\Lambda $for diverging acoustic waves. The latter properly accounts for spherical spreading, whereas the classical Gol’dberg number$\Gamma $is restricted to plane wave applications. Scaling laws are then derived to account for the effects imposed by jet exit conditions of practical interest and includes Mach number, temperature ratio, Strouhal number and an absolute observer distance relative to a broadband Gaussian source. Surveys of the acoustic pressure produced by a laboratory-scale, shock-free and unheated Mach 3 jet are used to support findings of the model. Acoustic waveforms are acquired on a two-dimensional grid extending out to 145 nozzle diameters from the jet exit plane. Various statistical metrics are employed to examine the degree of local and cumulative nonlinearity in the measured waveforms and their temporal derivatives. This includes a wave steepening factor (WSF), skewness, kurtosis and the normalized quadrature spectral density. The analysed data are shown to collapse reasonably well along rays emanating from the post-potential-core region of the jet. An application of the generalized Burgers equation is used to demonstrate the effect of cumulative nonlinear distortion on an arbitrary acoustic waveform produced by a high-convective-Mach-number supersonic jet. It is advocated that cumulative nonlinear distortion effects during far-field sound propagation are too subtle in this range-restricted environment and over the region covered, which may be true for other laboratory-scale jet noise facilities.

scholarly journals Wavefront manipulation by acoustic metasurfaces: from physics and applications

Nanophotonics ◽  
2018 ◽  
Vol 7 (6) ◽  
pp. 1191-1205 ◽  
Author(s):  
Bin Liang ◽  
Jian-chun Cheng ◽  
Cheng-Wei Qiu
Keyword(s):  
Acoustic Waves ◽  
Review Paper ◽  
Three Dimensional ◽  
New Physics ◽  
Research Field ◽  
Acoustic Metamaterials ◽  
Future Directions ◽  
Practical Applications ◽  
The Past ◽  
Recent Developments

AbstractMolding the wavefront of acoustic waves into the desired shape is of paramount significance in acoustics, which however are usually constrained by the acoustical response of naturally available materials. The emergence of acoustic metamaterials built by assembling artificial subwavelength elements provides distinct response to acoustic waves unattainable in nature. More recently, acoustic metasurfaces, a class of metamaterials with a reduced dimensionality, empower new physics and lead to extended functionalities different from their three-dimensional counterparts, enabling controlling, transmitted or reflected acoustic waves in ways that were not possible before. In this review paper, we present a comprehensive view of this rapidly growing research field by introducing the basic concepts of acoustic metasurfaces and the recent developments that have occurred over the past few years. We review the interesting properties of acoustic metasurfaces and their important functionalities of wavefront manipulation, followed by an outlook for promising future directions and potential practical applications.

scholarly journals ACOUSTIC METHOD OF AIRPORT FOG PRECIPITATION

Aviation ◽  
2007 ◽  
Vol 11 (3) ◽  
pp. 26-30 ◽  
Author(s):  
Henryka Czyz ◽  
Tadeusz Markowski
Keyword(s):  
Acoustic Field ◽  
Physical Condition ◽  
Acoustic Waves ◽  
Acoustic Method ◽  
Innovative Technology ◽  
Dispersed Phase ◽  
Small Particles ◽  
Recent Developments ◽  
Acoustic Coagulation

The influence of an acoustic field on the dispersed phase of a fluid has been studied in connection with the application of acoustic coagulation for the precipitation of gases. An acoustic field, depending on the intensity and frequency of the wave, as well as the physical condition of the medium, may cause coagulation, i.e. the joining of small particles into larger aggregates. This paper gives an example of the applications of dispersed phase acoustics, with particular emphasis on recent developments, e.g. the acoustic method of airport fog precipitation. This innovative technology is based on the fact that water can be collected from fog under the influence of acoustic waves. This work presents the new results of the analysis of the action of the acoustic field on the fog.

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