scholarly journals Horizontal Refraction of Acoustic Waves in Shallow-Water Waveguides Due to an Inhomogeneous Bottom Structure

2021 ◽  
Vol 9 (11) ◽  
pp. 1269
Author(s):  
Andrey Lunkov ◽  
Danila Sidorov ◽  
Valery Petnikov
Keyword(s):  
Shallow Water ◽  
Parabolic Equations ◽  
Acoustic Waves ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Three Dimensional ◽  
Transitional Region ◽  
Wave Effect ◽  
Low Frequencies ◽  
Horizontal Refraction

Three-Dimensional (3-D) sound propagation in a shallow-water waveguide with a constant depth and inhomogeneous bottom is studied through numerical simulations. As a model of inhomogeneity, a transitional region between an acoustically soft and hard bottom is considered. Depth-averaged transmission loss simulations using the “horizontal rays and vertical modes” approach and mode parabolic equations demonstrate the horizontal refraction of sound in this region, even if the water column is considered homogeneous. The observed wave effect is prominent at low frequencies, at which the water depth does not exceed a few acoustic wavelengths. The obtained results within the simplified model are verified by the simulations for a real seabed structure in the Kara Sea.

High‐resolution, three‐dimensional measurements of low‐frequency sound propagation in shallow water

1998 ◽  
Vol 103 (5) ◽  
pp. 3028-3028 ◽  
Author(s):  
George V. Frisk ◽  
Kyle M. Becker ◽  
Laurence N. Connor ◽  
James A. Doutt ◽  
Cynthia J. Sellers
Keyword(s):  
High Resolution ◽  
Shallow Water ◽  
Sound Propagation ◽  
Three Dimensional ◽  
Low Frequency ◽  
Frequency Sound ◽  
Dimensional Measurements

High-Resolution, Three-Dimensional Measurements of Low-Frequency Sound Propagation in Shallow Water

1998 ◽  
Author(s):  
George V. Frisk ◽  
Kyle M. Becker ◽  
Laurence N. Connor ◽  
James A. Doutt ◽  
Cynthia J. Sellers
Keyword(s):  
High Resolution ◽  
Shallow Water ◽  
Sound Propagation ◽  
Three Dimensional ◽  
Low Frequency ◽  
Frequency Sound ◽  
Dimensional Measurements

Normal Mode Analysis of Three-Dimensional Propagation Over a Small-Slope Cosine Shaped Hill

2015 ◽  
Vol 23 (03) ◽  
pp. 1550005 ◽  
Author(s):  
Megan S. Ballard ◽  
Benjamin M. Goldsberry ◽  
Marcia J. Isakson
Keyword(s):  
Parabolic Equation ◽  
Normal Mode ◽  
Hybrid Model ◽  
Mode Coupling ◽  
Transmission Loss ◽  
Normal Mode Analysis ◽  
Three Dimensional ◽  
Mode Analysis ◽  
The Hill ◽  
Horizontal Refraction

Three-dimensional propagation over an infinitely long cosine shaped hill is examined using an approximate normal mode/parabolic equation hybrid model that includes mode coupling in the out-going direction. The slope of the hill is relatively shallow, but it is significant enough to produce both mode-coupling and horizontal refraction effects. In the first part of the paper, the modeling approach is described, and the solution is compared to results obtained with a finite element method to evaluate the accuracy of the solution in light of assumptions made in formulating the model. Then the calculated transmission loss is interpreted in terms of a modal decomposition of the field, and the solution from the hybrid model is compared to adiabatic and N × 2D solutions to assess the relative importance of horizontal refraction and mode-coupling effects. An analysis using a horizontal ray trace is presented to explain differences in the modal interference pattern observed between the 3D and N × 2D solutions. The detailed discussion provides a thorough explanation of the observed 3D propagation effects and demonstrates the usefulness of the approximate normal mode/parabolic equation hybrid model as a tool to understand measured transmission loss in complex environments.

scholarly journals Theoretical Model of Acoustic Wave Propagation in Shallow Water

2017 ◽  
Vol 24 (2) ◽  
pp. 48-55 ◽  
Author(s):  
Eugeniusz Kozaczka ◽  
Grażyna Grelowska
Keyword(s):  
Shallow Water ◽  
Acoustic Field ◽  
Acoustic Waves ◽  
Sound Propagation ◽  
Low Frequency ◽  
Water Layer ◽  
Surface Shape ◽  
Shallow Sea ◽  
Multiple Reflections ◽  
Indirect Determination

Abstract The work is devoted to the propagation of low frequency waves in a shallow sea. As a source of acoustic waves, underwater disturbances generated by ships were adopted. A specific feature of the propagation of acoustic waves in shallow water is the proximity of boundaries of the limiting media characterised by different impedance properties, which affects the acoustic field coming from a source situated in the water layer “deformed” by different phenomena. The acoustic field distribution in the real shallow sea is affected not only by multiple reflections, but also by stochastic changes in the free surface shape, and statistical changes in the seabed shape and impedance. The paper discusses fundamental problems of modal sound propagation in the water layer over different types of bottom sediments. The basic task in this case was to determine the acoustic pressure level as a function of distance and depth. The results of the conducted investigation can be useful in indirect determination of the type of bottom.

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