Acoustic scattering of a plane wave by a circular penetrable cone

Wave Motion ◽  
2011 ◽  
Vol 48 (1) ◽  
pp. 62-82 ◽  
Author(s):  
M.A. Lyalinov
Author(s):  
Andrew N. Norris

The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122 , 3206–3210. ( doi:10.1121/1.2801546 )) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we derive a formula for the acoustic IE that is valid for causal and non-causal scattering. The general result is expressed as an integral of the time-dependent forward scattering function. The IE reduces to a finite integral for scatterers with zero long-wavelength monopole and dipole amplitudes. Implications for acoustic cloaking are discussed and a new metric is proposed for broadband acoustic transparency.


Mathematics ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 1156
Author(s):  
Emilia Blåsten ◽  
Lassi Päivärinta ◽  
Sadia Sadique

We consider the problem of fixed frequency acoustic scattering from a sound-soft flat screen. More precisely, the obstacle is restricted to a two-dimensional plane and interacting with an arbitrary incident wave, it scatters acoustic waves to three-dimensional space. The model is particularly relevant in the study and design of reflecting sonars and antennas, cases where one cannot assume that the incident wave is a plane wave. Our main result is that given the plane where the screen is located, the far-field pattern produced by any single arbitrary incident wave determines the exact shape of the screen, as long as it is not antisymmetric with respect to the plane. This holds even for screens whose shape is an arbitrary simply connected smooth domain. This is in contrast to earlier work where the incident wave had to be a plane wave, or more recent work where only polygonal scatterers are determined.


Author(s):  
Christodoulos Athanasiadis

AbstractWe consider the boundary-value problems corresponding to the scattering of a time-harmonic acoustic plane wave by a multi-layered obstacle with a sound-soft, hard or penetrable core. Firstly, we construct in closed forms the normalized scattering amplitudes and prove the classical reciprocity and scattering theorems for these problems. These results are then used to study the spectrum of the scattering amplitude operator. The scattering cross-section is expressed in terms of the forward value of the corresponding normalized scattering amplitude. Finally, we develop a more general theory for scattering relations.


2021 ◽  
Vol 150 (2) ◽  
pp. 1381-1389
Author(s):  
Shuyuan Li ◽  
Jingyao Shi ◽  
Yuqi Gao ◽  
Xiaofeng Zhang ◽  
Jun Fan ◽  
...  

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