scholarly journals Generalized parabolic wave equation and field‐moment equations for random media having spatial variation of mean sound speed

1984 ◽  
Vol 75 (S1) ◽  
pp. S26-S27
Author(s):  
Reginald J. Hill
Keyword(s):  
Wave Equation ◽  
Spatial Variation ◽  
Sound Speed ◽  
Random Media ◽  
Moment Equations

On transforms reducing one-dimensional systems of shallow-water to the wave equation with sound speed c 2 = x

2013 ◽  
Vol 93 (5-6) ◽  
pp. 704-714 ◽  
Author(s):  
S. Yu. Dobrokhotov ◽  
S. B. Medvedev ◽  
D. S. Minenkov
Keyword(s):  
Wave Equation ◽  
Shallow Water ◽  
Sound Speed ◽  
One Dimensional

On the Propagation of Sound in a High-Speed Non-Isothermal Shear Flow

2009 ◽  
Vol 8 (3) ◽  
pp. 199-230 ◽  
Author(s):  
L.M.B.C. Campos ◽  
M.H. Kobayashi
Keyword(s):  
Wave Equation ◽  
Shear Flow ◽  
Acoustic Wave ◽  
Sound Speed ◽  
High Speed ◽  
Shear Flows ◽  
Critical Layer ◽  
Acoustic Wave Equation ◽  
Mean Flow ◽  
Flow Vorticity

The propagation of sound in shear flows is relevant to the acoustics of wall and duct boundary layers, and to jet shear layers. The acoustic wave equation in a shear flow has been solved exactly only for a plane unidirectional homentropic mean shear flow, in the case of three velocity profiles: linear, exponential and hyperbolic tangent. The assumption of homentropic mean flow restricts application to isothermal shear flows. In the present paper the wave equation in an plane unidirectional shear flow with a linear velocity profile is solved in an isentropic non-homentropic case, which allows for the presence of transverse temperature gradients associated with the ***non-uniform sound speed. The sound speed profile is specified by the condition of constant enthalpy, i.e. homenergetic shear flow. In this case the acoustic wave equation has three singularities at finite distance (besides the point at infinity), viz. the critical layer where the Doppler shifted frequency vanishes, and the critical flow points where the sound speed vanishes. By matching pairs of solutions around the singular and regular points, the amplitude and phase of the acoustic pressure in calculated and plotted for several combinations of wavelength and wave frequency, mean flow vorticity and sound speed, demonstrating, among others, some cases of sound suppression at the critical layer.

RAY STABILITY FOR BACKGROUND SOUND SPEED PROFILES WITH TRANSITION

2009 ◽  
Vol 19 (09) ◽  
pp. 2953-2964 ◽  
Author(s):  
TAMÁS BÓDAI ◽  
ALAN J. FENWICK ◽  
MARIAN WIERCIGROCH
Keyword(s):  
Sound Speed ◽  
Random Media ◽  
Sound Propagation ◽  
Deep Ocean ◽  
Gradual Transition ◽  
Nonlinearity Parameter ◽  
Ambient Sound ◽  
Eastern North Atlantic ◽  
Sound Speed Structure ◽  
Theory Framework

In this paper deep ocean sound propagation through random media is considered. The study is conducted within a ray theory framework, which facilitates the assessment of ray stability. Model ocean environments where there is a gradual transition between two ambient sound speed profiles, a single duct Munk profile and a double duct profile taken in the Eastern North Atlantic are examined. We build on the finding that the ambient sound speed structure controls ray stability [Beron-Vera & Brown, 2003], and extend this statement for sound speed profiles with transition. It is shown that launching basins, plots constructed by the Maximal Lyapunov Exponent and indicating desirable ray launching parameters, can be predicted by the unperturbed ray system using the nonlinearity parameter.

Computing Where Perturbations Affect the Acoustic Impulse Response in the Ocean

2018 ◽  
Vol 26 (02) ◽  
pp. 1850004
Author(s):  
John L. Spiesberger ◽  
Dmitry Yu Mikhin
Keyword(s):  
Wave Equation ◽  
Acoustic Wave ◽  
Impulse Response ◽  
Sound Speed ◽  
Acoustic Signals ◽  
Technological Advance ◽  
Propagation Model ◽  
Acoustic Wave Equation ◽  
Finite Frequency ◽  
The One

We compute accurate maps of oceanic perturbations affecting transient acoustic signals propagating from source to receiver. The technological advance involves coupling the one-way wave equation (OWWE) propagation model with the theory for the Differential Measure of Influence (DMI) yielding the map. The DMI requires two finite-frequency solutions of the acoustic wave equation obeying reciprocity: from source to receiver and vice versa. OWWE satisfies reciprocity at basin-scales with sound speed varying horizontally and vertically. At infinite frequency, maps of the DMI collapse into rays. Mapping the DMI is useful for understanding measurements of acoustic perturbations at finite frequencies.

Sign in / Sign up

Export Citation Format

Share Document