Solution of Wide-angle Parabolic Equations for Long-range Sound Propagation in a Moving Medium PDF Download
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Author: David Keith Wilson
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: David Keith Wilson
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Vladimir E. Ostashev
Publisher:
ISBN:
Category : Differential equations, Partial
Languages : en
Pages : 16
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Book Description
The narrow-angle parabolic equation (NAPE) with the effective sound speed approximation (ESSA) is widely used for sound and infrasound propagation in a moving medium such as the atmosphere. However, it is valid only for angles less than 20° with respect to the nominal propagation direction. In this paper, the wave equation and extra-wide-angle parabolic equation (EWAPE) for high-frequency (short-wavelength) sound waves in a moving medium with arbitrary Mach numbers are derived without the ESSA. For relatively smooth variations in the medium velocity, the EWAPE is valid for propagation angles up to 90°. Using the Padé (n,n) series expansion and narrow-angle approximation, the EWAPE is reduced to the wide-angle parabolic equation (WAPE) and NAPE. Versions of these equations are then formulated for low Mach numbers, which is the case that is usually considered in the literature. The phase errors pertinent to the equations considered are studied. It is shown that the equations for low Mach numbers and the WAPE with the ESSA are applicable only under rather restrictive conditions on the medium velocity. An effective numerical implementation of the WAPE for arbitrary Mach numbers in the Padé (1,1) approximation is developed and applied to sound propagation in the atmosphere.
Author: Vladimir E. Ostashev
Publisher:
ISBN:
Category : Born approximation
Languages : en
Pages : 17
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Book Description
Wide-angle parabolic equations (WAPEs) play an important role in physics. They are derived by an expansion of a square-root pseudo-differential operator in one-way wave equations, and then solved by finite-difference techniques. In the present paper, a different approach is suggested. The starting point is an extra-wide-angle parabolic equation (EWAPE) valid for small variations of the refractive index of a medium. This equation is written in an integral form, solved by a perturbation technique, and transformed to the spectral domain. The resulting split-step spectral algorithm for the EWAPE accounts for the propagation angles up to 90° with respect to the nominal direction. This EWAPE is also generalized to large variations in the refractive index. It is shown that WAPEs known in the literature are particular cases of the two EWAPEs. This provides an alternative derivation of the WAPEs, enables a better understanding of the underlying physics and ranges of their applicability, and opens an opportunity for innovative algorithms. Sound propagation in both motionless and moving media is considered. The split-step spectral algorithm is particularly useful in the latter case since complicated partial derivatives of the sound pressure and medium velocity reduce to wave vectors (essentially, propagation angles) in the spectral domain.
Author:
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ISBN:
Category :
Languages : en
Pages : 5
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Benchmark solutions generated with parabolic equation (PE) models are presented for range-dependent underwater acoustic propagation problems involving both penetrable and perfectly reflection ocean bottoms. The solution of the wide-angle PE of Claerbout (J.F. Claerbout, Fundamentals of Geophysical Data Processing (McGraw-Hill, New York, 1976), pp. 206-207) agrees with the outgoing coupled-mode solution for the problems involving penetrable bottoms. The solution of the higher-order PE of Bamberger et al. (Bamberger et al., Higher Order Paraxial Wave Equation Approximations in Heterogeneous Media, SIAM J. Appl. Math. 48, 129-154 (1988)), which is a generalization of Claerbout's PE, agrees with the outgoing coupled-mode solution for problems involving large variations in sound speed and propagation nearly orthogonal to the preferred direction. The computer code FEPE was used to generate the benchmark solutions and was found to run several times faster than the IFDPE computer code due to a tridiagonal system solver in FEPE that is optimized for range-dependent problems.
Author: Xunren Yang
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 3110383020
Category : Science
Languages : en
Pages : 462
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Book Description
This book concisely expounds the fundamental concepts, phenomena, theories and procedures in a complete and systematic sense. In this book, not only almost all the important achievements from predecessors but also the contributions from the author himself have been summed up profoundly. Starting from the derivation of fundamental equations, various classical acoustical phenomena such as reflection, refraction, scattering diffraction and absorption in atmosphere, as well as the influences of gravitation and rotation of the earth on the behaviors of different atmospheric waves including acoustic waves, have been discussed in viewpoints of wave acoustics and geometrical acoustics respectively. The recent developments of several computation methods in the field of atmospheric acoustics have been introduced in some detail. As for the application aspects, atmospheric remote sensing has been discussed from the angle of inverse problems.
Author: L Brekhovskikh
Publisher: Elsevier
ISBN: 0323161626
Category : Science
Languages : en
Pages : 520
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Book Description
Waves in Layered Media discusses different theories about the relationship between waves and media. The book specifically covers several factors that can affect the behavior and formation of various kinds of waves in different types of media. Comprised of nine chapters, the book establishes the fundamentals by first tackling simplest concepts, such as the behavior plane wave and discretely layered media. The succeeding chapters cover much more complex ideas, such as the refraction and reflection of waves, spherical wave, and wave in inhomogeneous media. The book will be a great asset to researchers whose work involves acoustics, or to professionals whose line of work involves sound waves.
Author: P. Malbéqui
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Paul C. Etter
Publisher: CRC Press
ISBN: 1351831984
Category : Technology & Engineering
Languages : en
Pages : 557
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Book Description
Underwater Acoustic Modeling and Simulation, Fourth Edition continues to provide the most authoritative overview of currently available propagation, noise, reverberation, and sonar-performance models. This fourth edition of a bestseller discusses the fundamental processes involved in simulating the performance of underwater acoustic systems and emphasizes the importance of applying the proper modeling resources to simulate the behavior of sound in virtual ocean environments. New to the Fourth Edition Extensive new material that addresses recent advances in inverse techniques and marine-mammal protection Problem sets in each chapter Updated and expanded inventories of available models Designed for readers with an understanding of underwater acoustics but who are unfamiliar with the various aspects of modeling, the book includes sufficient mathematical derivations to demonstrate model formulations and provides guidelines for selecting and using the models. Examples of each type of model illustrate model formulations, model assumptions, and algorithm efficiency. Simulation case studies are also included to demonstrate practical applications. Providing a thorough source of information on modeling resources, this book examines the translation of our physical understanding of sound in the sea into mathematical models that simulate acoustic propagation, noise, and reverberation in the ocean. The text shows how these models are used to predict and diagnose the performance of complex sonar systems operating in the undersea environment.
Author: Alexis Le Pichon
Publisher: Springer
ISBN: 3319751409
Category : Science
Languages : en
Pages : 1168
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Book Description
Since the publication of the first volume “Infrasound monitoring for atmospheric studies” published in 2010, significant advances were achieved in the fields of engineering, propagation modelling, and atmospheric remote sensing methods. The global infrasound network, which consists of the International Monitoring Network (IMS) for nuclear test ban verification completed by an increasing number of regional cluster arrays deployed around the globe, has evidenced an unprecedented potential for detecting, locating and characterizing various natural and man-made sources. In recent years, infrasound has evolved into a broad interdisciplinary field encompassing academic disciplines of geophysics and innovative technical and scientific developments. The advances in innovative ground-based instruments, including infrasound inversions for continuous observations of the stratosphere and mesosphere, provide useful insights into the geophysical source phenomenology and atmospheric processes involved. Systematic investigations into low-frequency infrasound signals and the development of complementary observational platforms point out new insights into the dynamics of the middle atmosphere which play a significant role in both tropospheric weather and climate. This monitoring system also provides continuous relevant information about natural hazards with high societal benefits, like on-going volcanic eruptions, surface earthquakes, meteorites or severe weather. With this new edition, researchers and students benefit from a comprehensive content of both fundamental and applied inter-disciplinary topics.
Author: Leonid M. Brekhovskikh
Publisher: Springer Science & Business Media
ISBN: 3662027763
Category : Science
Languages : en
Pages : 405
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Book Description
This is the sequel to our book Acoustics of Layered Media I: Plane and Quasi Plane Waves (Springer Ser. Wave Phenom. , Vol. 5). Taken together, these two monographs present a systematic exposition of the theory of sound propagation in inhomogeneous media, which starts from first principles and includes recent results. More advanced topics are considered in this second volume. Although the theory of wave beams and fields of localized sources is more sophisticated than the theory of quasi-plane waves, it embraces a much wider range of interesting problems that are also important for applications. We exploit the results of Acoustics of Layered Media I, as long as it is expedient to consider sound fields as a superposition of plane or quasi-plane waves. However, the knowledgeable reader will view this book as self-contained. Similar topics have been treated in the book by L. M. Brekhovskikh, Waves in Layered Media, the English version of the second edition of which was published by Academic Press in 1980. Since Waves in Layered Media became very popular, we have tried here to retain its spirit. However, the majority of this text is devoted to new material which reflects the significant progress of the theory during recent years. In particular, acoustic fields in a moving fluid are considered and much attention is paid to sound propagation in range dependent environments, which is currently on the leading edge of research activities.
