Asymptotic Solution for the Sound Field in Shallow Water with a Negative Velocity Gradient

1969 ◽  
Vol 45 (2) ◽  
pp. 365-371 ◽  
Author(s):  
R. N. Denham
Keyword(s):  
Asymptotic Solution ◽  
Shallow Water ◽  
Velocity Gradient ◽  
Sound Field

scholarly journals A Green’s Function for Acoustic Problems in Pekeris Waveguide Using a Rigorous Image Source Method

2021 ◽  
Vol 11 (6) ◽  
pp. 2722
Author(s):  
Zhiwen Qian ◽  
Dejiang Shang ◽  
Yuan Hu ◽  
Xinyang Xu ◽  
Haihan Zhao ◽  
...  
Keyword(s):  
Green’S Function ◽  
Shallow Water ◽  
Green's Function ◽  
Plane Waves ◽  
Spherical Wave ◽  
Sound Field ◽  
Efficient Computation ◽  
Image Source ◽  
Source Method ◽  
Pekeris Waveguide

The Green’s function (GF) directly eases the efficient computation for acoustic radiation problems in shallow water with the use of the Helmholtz integral equation. The difficulty in solving the GF in shallow water lies in the need to consider the boundary effects. In this paper, a rigorous theoretical model of interactions between the spherical wave and the liquid boundary is established by Fourier transform. The accurate and adaptive GF for the acoustic problems in the Pekeris waveguide with lossy seabed is derived, which is based on the image source method (ISM) and wave acoustics. First, the spherical wave is decomposed into plane waves in different incident angles. Second, each plane wave is multiplied by the corresponding reflection coefficient to obtain the reflected sound field, and the field is superposed to obtain the reflected sound field of the spherical wave. Then, the sound field of all image sources and the physical source are summed to obtain the GF in the Pekeris waveguide. The results computed by this method are compared with the standard wavenumber integration method, which verifies the accuracy of the GF for the near- and far-field acoustic problems. The influence of seabed attenuation on modal interference patterns is analyzed.

scholarly journals A Prediction Method for Acoustic Intensity Vector Field of Elastic Structure in Shallow Water Waveguide

2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Wenbo Wang ◽  
Desen Yang ◽  
Jie Shi
Keyword(s):  
Spatial Structure ◽  
Shallow Water ◽  
Transfer Functions ◽  
Source Parameters ◽  
Prediction Method ◽  
Sound Field ◽  
Elastic Structure ◽  
Superposition Method ◽  
Acoustic Intensity ◽  
Sound Energy

Compared with scalar sound field, vector sound field explained the spatial structure of sound field better since it not only presents the sound energy distribution but also describes the sound energy flow characteristics. Particularly, with more complicated interaction among different wavefronts, the vector sound field characteristics of an elastic structure in a shallow water waveguide are worthy of studying. However, there is no reliable prediction method for the vector sound field of an elastic structure with a high efficiency in a shallow water waveguide. To solve the problem, transfer functions in the waveguide have been modified with some approximations to apply for the vector sound field prediction of elastic structures in shallow water waveguides. The method is based on the combined wave superposition method (CWSM), which has been proved to be efficient for predicting scalar sound field. The rationality of the approximations is validated with simulations. Characteristics of the complex acoustic intensity, especially the vertical components are observed. The results show that, with constructive and destructive interferences in the depth direction, there could be quantities of crests and vortices in the spatial structure of time-dependent complex intensity, which manifest a unique dynamic characteristic of sound energy. With more complicated interactions among the wavefronts, a structure source could not be equivalent to a point source in most instances. The vector sound field characteristics of the two sources could be entirely different, even though the scalar sound field characteristics are similar. Meanwhile, source types, source parameters, ocean environment parameters, and geo parameters may have influence on the vector sound field characteristics, which could be explained with the normal mode theory.

Comparison of Sound Propagation Characteristic between Deep and Shallow Water

2014 ◽  
Vol 577 ◽  
pp. 1198-1201
Author(s):  
Zhang Liang ◽  
Chun Xia Meng ◽  
Hai Tao Xiao
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Sound Speed ◽  
Sound Propagation ◽  
Spherical Wave ◽  
Sound Field ◽  
Propagation Loss ◽  
Speed Profile ◽  
Sound Speed Profile ◽  
Propagation Law

The physical characteristics are compared between shallow and deep water, in physics and acoustics, respectively. There is a specific sound speed profile in deep water, which is different from which in shallow water, resulting in different sound propagation law between them. In this paper, the sound field distributions are simulated under respective typical sound speed profile. The color figures of sound intensity are obtained, in which the horizontal ordinate is distance, and the vertical ordinate is depth. Then we can get some important characteristics of sound propagation. The results show that the seabed boundary is an important influence on sound propagation in shallow water, and sound propagation loss in deep water convergent zone is visibly less than which in spherical wave spreading. We can realize the remote probing using the acoustic phenomenon.

Surface reverberation at sound field focusing in shallow water

2008 ◽  
Vol 54 (6) ◽  
pp. 844-853 ◽  
Author(s):  
A. A. Lunkov ◽  
S. A. Pereselkov ◽  
V. G. Petnikov
Keyword(s):  
Shallow Water ◽  
Sound Field

Spectral features of sound field fluctuations in shallow water with internal solitons

2005 ◽  
Vol 117 (4) ◽  
pp. 2547-2547
Author(s):  
Mohsen Badiey ◽  
Valery Grigorev ◽  
Boris Katsnelson ◽  
James Lynch
Keyword(s):  
Shallow Water ◽  
Sound Field ◽  
Spectral Features ◽  
Field Fluctuations

Integral Solution of the Shallow Water Sound Field

1961 ◽  
Vol 33 (3) ◽  
pp. 323-329 ◽  
Author(s):  
C. B. Leslie ◽  
N. R. Sorensen
Keyword(s):  
Shallow Water ◽  
Sound Field ◽  
Integral Solution

STUDY ON SINGLE-MODE EXCITATION IN TIME-VARIANT SHALLOW WATER ENVIRONMENT

2014 ◽  
Vol 22 (01) ◽  
pp. 1440001
Author(s):  
DAYONG PENG ◽  
TIANFU GAO ◽  
JUAN ZENG
Keyword(s):  
Shallow Water ◽  
Recursive Algorithm ◽  
Water Environment ◽  
Sound Field ◽  
Single Mode ◽  
Shallow Water Environment ◽  
Mode Excitation ◽  
Ocean Environment ◽  
Short Time ◽  
Function Matrix

Single-mode excitation is a powerful tool for studying many oceanographic processes. Meanwhile, the complex time-variant ocean environment poses a great challenge for single-mode excitation because Green's function matrix of sound field changes quickly. In their previous work, the authors built a system to excite single-mode in a relative simple environment. The purpose of this paper is to study the feasibility of single-mode excitation in rapidly time-variant ocean environment. An improved recursive algorithm is presented to adapt for time-variant environment where the single-mode can be excited within very short time by this algorithm. A typical time-variant shallow water environment is simulated, and results of the single-mode excitation in this environment are presented.

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