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| Author | : Calvin H. Wilcox |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 206 |
| Release | : 2012-12-06 |
| Genre | : Technology & Engineering |
| ISBN | : 1461211247 |
Download Sound Propagation in Stratified Fluids Book in PDF, ePub and Kindle
Stratified fluids whose densities, sound speeds and other parameters are functions of a single depth coordinate occur widely in nature. Indeed, the earth's gravitational field imposes a stratification on its atmosphere, oceans and lakes. It is well known that their stratification has a profound effect on the propagation of sound in these fluids. The most striking effect is probably the occurrence of acoustic ducts, due to minima of the sound speed, that can trap sound waves and cause them to propagate hori zontally. The reflection, transmission and distortion of sonar signals by acoustic ducts is important in interpreting sonar echoes. Signal scattering by layers of microscopic marine organisms is important to both sonar engi neers and marine biologists. Again, reflection of signals from bottom sediment layers overlying a penetrable bottom are of interest both as sources of unwanted echoes and in the acoustic probing of such layers. Many other examples could be given. The purpose of this monograph is to develop from first principles a theory of sound propagation in stratified fluids whose densities and sound speeds are essentially arbitrary functions of the depth. In physical terms, the propagation of both time-harmonic and transient fields is analyzed. The corresponding mathematical model leads to the study of boundary value problems for a scalar wave equation whose coefficients contain the pre scribed density and sound speed functions.
| Author | : Calvin H. Wilcox |
| Publisher | : Springer |
| Total Pages | : 212 |
| Release | : 1984-04-23 |
| Genre | : Mathematics |
| ISBN | : 9780387909868 |
Download Sound Propagation in Stratified Fluids Book in PDF, ePub and Kindle
Stratified fluids whose densities, sound speeds and other parameters are functions of a single depth coordinate occur widely in nature. Indeed, the earth's gravitational field imposes a stratification on its atmosphere, oceans and lakes. It is well known that their stratification has a profound effect on the propagation of sound in these fluids. The most striking effect is probably the occurrence of acoustic ducts, due to minima of the sound speed, that can trap sound waves and cause them to propagate hori zontally. The reflection, transmission and distortion of sonar signals by acoustic ducts is important in interpreting sonar echoes. Signal scattering by layers of microscopic marine organisms is important to both sonar engi neers and marine biologists. Again, reflection of signals from bottom sediment layers overlying a penetrable bottom are of interest both as sources of unwanted echoes and in the acoustic probing of such layers. Many other examples could be given. The purpose of this monograph is to develop from first principles a theory of sound propagation in stratified fluids whose densities and sound speeds are essentially arbitrary functions of the depth. In physical terms, the propagation of both time-harmonic and transient fields is analyzed. The corresponding mathematical model leads to the study of boundary value problems for a scalar wave equation whose coefficients contain the pre scribed density and sound speed functions.
| Author | : Calvin H. Wilcox |
| Publisher | : |
| Total Pages | : 156 |
| Release | : 1980 |
| Genre | : |
| ISBN | : |
Download Spectral Analysis of Sound Propagation in Stratified Fluids Book in PDF, ePub and Kindle
This paper presents a spectral analysis of the acoustic fields in stationary plane stratified fluids whose densities and sound speeds are functions of the depth. The analysis is based on families of normal mode fields that have simple physical interpretations. The acoustic field in such a fluid may be described by an acoustic potential or by the excess pressure.
| Author | : Calvin H. Wilcox |
| Publisher | : |
| Total Pages | : 49 |
| Release | : 1981 |
| Genre | : |
| ISBN | : |
Download Transient Acoustic Wave Propagation in Stratified Fluids Book in PDF, ePub and Kindle
Transient acoustic wave propagation is analyzed for the case of plane-stratified fluids having density rho(y) and sound speed c(y) at depth y. For infinite fluids it is assumed that the (in general discontinuous) functions rho(y), c(y) are uniformly positive and bounded and satisfy abs.val (rho(y) - rho(at infinity)) or = C(+ or - y) to the - alpha power, abs. val. (c(y) - c(at infinity)) or = C(+ or - y) to the - alpha power for + or - y 0, where alpha 3/2. Semi-infinite and finite layers are also treated. The acoustic potential is a solution of the wave equation del-squared u/del t-squared - c-squared(y) rho(y) del dot (1/rho(y)grad(u)) = f(t, x, y) where x = (x1,x2) are horizontal coordinates and f(t, x, y) characterizes the wave sources. The principal results of the analysis show that u is the sum of a free component, which behaves like a diverging spherical wave for large t, and a guided component which is approximately localized in regions abs. val. (y - y sub j)
| Author | : Matania Ben-Artzi |
| Publisher | : |
| Total Pages | : 78 |
| Release | : 1987* |
| Genre | : |
| ISBN | : |
Download Acoustic Waves in Perturbed Stratified Fluids Book in PDF, ePub and Kindle
| Author | : George V. Frisk |
| Publisher | : Pearson Education |
| Total Pages | : 391 |
| Release | : 1994-01-02 |
| Genre | : Technology & Engineering |
| ISBN | : 0132441543 |
Download Ocean and Seabed Acoustics Book in PDF, ePub and Kindle
Respected scientist and educator George V. Frisk draws on his extensive professional experience to demonstrate how the ocean environment provides an excellent setting in which to display general principles of wave propagation that are also applicable to other areas of wave physics. Ocean and Seabed Acoustics proceeds with a derivation of elementary solutions to the wave equation in free space and then progressively addresses problems of increasing complexity. This book concludes with a discussion of acoustic wave propagation due to a point source in an inhomogeneous waveguide with lossy boundaries.
| Author | : J.F. Allard |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 296 |
| Release | : 2012-12-06 |
| Genre | : Technology & Engineering |
| ISBN | : 9401118663 |
Download Propagation of Sound in Porous Media Book in PDF, ePub and Kindle
This book has grown out of the research activities of the author in the fields of sound propagation in porous media and modelling of acoustic materials. It is assumed that the reader has a background of advanced calculus, including an introduction to differential equations, complex variables and matrix algebra. A prior exposure to theory of elasticity would be advantageous. Chapters 1-3 deal with sound propagation of plane waves in solids and fluids, and the topics of acoustic impedance and reflection coefficient are given a large emphasis. The topic of flow resistivity is presented in Chapter 2. Chapter 4 deals with sound propagation in porous materials having cylindrical pores. The topics of effective density, and of tortuosity, are presented. The thermal exchanges between the frame and the fluid, and the behaviour of the bulk modulus of the fluid, are described in this simple context. Chapter 5 is concerned with sound propagation in other porous materials, and the recent notions of characteristic dimensions, which describe thermal exchanges and the viscous forces at high frequencies, are introduced. In Chapter 6, the case of porous media having an elastic frame is considered in the context of Biot theory, where new topics described in Chapter 5 have been included.
| Author | : Carol Sue Jones |
| Publisher | : |
| Total Pages | : 164 |
| Release | : 1996 |
| Genre | : Fluid dynamics |
| ISBN | : |
Download Sound Propagation in Moving Fluid Book in PDF, ePub and Kindle
| Author | : Leonid M. Brekhovskikh |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 249 |
| Release | : 2012-12-06 |
| Genre | : Science |
| ISBN | : 3642523692 |
Download Acoustics of Layered Media I Book in PDF, ePub and Kindle
This monograph is devoted to the systematic presentation of the theory of sound wave propagation in layered structures. These structures can be man-made, such as ultrasonic filters, lenses, surface-wave delay lines, or natural media, such as the ocean and the atmosphere, with their marked horizontal stratification. A related problem is the propagation of elastic (seismic) waves in the earth's crust These topics have been treated rather completely in the book by L. M. Brek hovskikh, Waves in Layered Media, the English version of the second edition of which was published by Academic Press in 1980. Due to progress in experimental and computer technology it has become possible to analyze the influence of factors such as medium motion and density stratification upon the propagation of sound waves. Much attention has been paid to propagation theory in near-stratified media, Le. , media with small deviations from strict stratification. Interesting results have also been obtained in the fields of acoustics which had been previously considered to be "completely" developed. For these reasons, and also because of the inflow of researchers from the related fields of physics and mathematics, the circle of persons and research groups engaged in the study of sound propagation has rather expanded. Therefore, the appearance of a new summary review of the field of acoustics of layered media has become highly desirable. Since Waves in Layered Media became quite popular, we have tried to retain its positive features and general structure.
| Author | : Calvin H. Wilcox |
| Publisher | : |
| Total Pages | : 50 |
| Release | : 1979 |
| Genre | : |
| ISBN | : |
Download Transient Acoustic Wave Propagation in an Epstein Duct Book in PDF, ePub and Kindle
Transient acoustic wave propagation is analyzed for the case of an unlimited plane-stratified fluid having constant density and sound speed c(y) at depth y given by the Epstein profile 1/c(y)-squared = K sech-squared (y/H) + L tanh (y/H) + M. The acoustic potential is a solution of the wave equation Dt-squared u - C-squared (y) (D1-squared u + D2-squared u + Dy-squared u) = f(t, x, y) where x = (x1,x2) are horizontal coordinates and f(t, x, y) characterizes the wave sources. The principal results of the analysis show that u is the sum of a free component, which behaves like a diverging spherical wave for large t, and a guided component which is approximately localized in a region abs. val. (y-y sub 0)
