An advanced boundary element/fast Fourier transform axisymmetric formulation for acoustic radiation and wave scattering problems

1999 ◽  
Vol 105 (3) ◽  
pp. 1517-1526 ◽  
Author(s):  
Stephanos V. Tsinopoulos ◽  
John P. Agnantiaris ◽  
Demosthenes Polyzos
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Boundary Element ◽  
Wave Scattering ◽  
Acoustic Radiation ◽  
Scattering Problems

Acoustic radiation from thin rods in water

1986 ◽  
Vol 64 (6) ◽  
pp. 671-676 ◽  
Author(s):  
B. J. Jarosz ◽  
R. L. Clarke
Keyword(s):  
Stainless Steel ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Pressure Distribution ◽  
Surface Waves ◽  
Longitudinal Wave ◽  
Acoustic Radiation ◽  
Stoneley Wave ◽  
Fast Fourier Transform Analysis ◽  
Spatial Frequencies

The ultrasound pressure distribution produced by end-excited stainless-steel rods immersed in water has been investigated. Rod diameters of 0.238 and 0.319 cm were tested at frequencies between 1.0 and 3.5 MHz. Immersion depths up to 10 cm were studied. Semiperiodic patterns were observed along the rods, with repetition lengths of 0.6 and 1.1 cm. Fast Fourier-transform analysis of the patterns showed the presence of three spatial frequencies interpreted to be the lowest mode longitudinal wave, Rayleigh-type surface waves, and the Stoneley wave propagating in the liquid.

Boundary Element Methods in Probabilistic Acoustic Radiation Problems

1990 ◽  
Vol 112 (4) ◽  
pp. 556-560 ◽  
Author(s):  
R. P. Daddazio ◽  
M. M. Ettouney
Keyword(s):  
Boundary Element ◽  
Acoustic Radiation ◽  
Probabilistic Approach ◽  
Boundary Element Methods ◽  
Fluid Structure Interactions ◽  
Scattering Problems ◽  
Fluid Structure ◽  
Wide Range ◽  
System Properties ◽  
Engineering Practices

Boundary Element Methods (BEM) are suited to a wide range of engineering problems, especially those of a semi-infinite nature. Examples of such problems can be found in the fluid-structure interactions of acoustic radiation and scattering problems and in the soil-structure interactions of earthquake and machine foundation problems. The required input parameters, dynamic loads, and system properties for such problems are not in general well-defined and can be considered random variables. Probabilistic structural analysis through the use of the BEM has been introduced by Ettouney et al. (1989a, 1989b) for the solution of plane elastic systems with uncertain material properties. The method was applied to solution of problems in the fields of structural and geotechnical engineering. In this work, we extend the use of this probabilistic approach to area of fluid-structure interaction by applying this technique to the problem of acoustic radiation from structures. The advantages of the probabilistic viewpoint are discussed with regard to current engineering practices. The importance of confidence estimates for criteria of nonexceedance response is emphasized.

A Parameter Study of the Burton–Miller Formulation in the BEM Analysis of Acoustic Resonances in Exterior Configurations

2020 ◽  
pp. 2050023
Author(s):  
Xin Chen ◽  
Qiang He ◽  
Chang-Jun Zheng ◽  
Cheng Wan ◽  
Chuan-Xing Bi ◽  
...  
Keyword(s):  
Boundary Element ◽  
Acoustic Radiation ◽  
Coupling Parameter ◽  
Acoustic Resonance ◽  
Integral Approach ◽  
Parameter Study ◽  
Scattering Problems ◽  
Element Analysis ◽  
Boundary Element Analysis ◽  
Acoustic Resonances

The application of a boundary element technique in combination with a contour integral approach to the numerical analysis of acoustic resonances in exterior configurations is investigated in this paper. Similar to the boundary element analysis of exterior acoustic radiation or scattering problems, spurious eigenfrequencies also turn up in the boundary element solution to exterior acoustic resonance problems. To filter out the spurious eigenfrequencies, the Burton–Miller-type combined formulation is employed to shift them from the real axis to the complex domain. The shifting effect brought by the combined formulation with different types of coupling parameters is investigated. Unlike in acoustic radiation and scattering analyses for which [Formula: see text] is suggested as the coupling parameter, it will be shown that the coupling parameter specified as [Formula: see text] with [Formula: see text] (the time-dependent term herein is [Formula: see text]) is more desirable in distinguishing the spurious eigenfrequencies in the boundary element analysis of exterior acoustic resonances.

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