Comments on ‘‘The influence of wind and temperature gradients on sound propagation, calculated with the two way wave equations’’ [J. Acoust. Soc. Am. 87, 1987–1998 (1990)]

1992 ◽  
Vol 91 (1) ◽  
pp. 498-500 ◽  
Author(s):  
Richard Raspet ◽  
Lixin Yao ◽  
Steven J. Franke ◽  
Michael J. White
Keyword(s):  
Wave Equations ◽  
Sound Propagation ◽  
Temperature Gradients

Effects of Vortices on Sound Propagation

2009 ◽  
Author(s):  
R. Michael Jones ◽  
Alfred J. Bedard
Keyword(s):  
Vortex Core ◽  
Sound Propagation ◽  
Acoustic Propagation ◽  
Temperature Gradients ◽  
Generation Mechanism ◽  
Strong Wind ◽  
Sound Waves ◽  
Sound Generation ◽  
Virtual Source ◽  
Sound Energy

Our simulations indicate that the presence of a vortex in or near acoustic propagation paths can have profound effects on the distributions of sound energy and cause sound waves to originate from virtual source positions. For example, recent studies have shown that infrasonic energy arrives from the regions of hurricanes. The azimuths measured for a limited number of cases published to date do not seem to originate from the vortex cores; but rather from the periphery of the system. This raises the questions: Is the sound being affected by strong wind and temperature gradients with the measured azimuths indicating virtual source positions? -or- Is the sound generation mechanism located outside of the vortex core?

scholarly journals Fundamental models in nonlinear acoustics part I. Analytical comparison

2018 ◽  
Vol 28 (12) ◽  
pp. 2403-2455 ◽  
Author(s):  
Barbara Kaltenbacher ◽  
Mechthild Thalhammer
Keyword(s):  
Thermal Conductivity ◽  
Initial Data ◽  
Wave Equations ◽  
Sound Propagation ◽  
Nonlinear Acoustics ◽  
Analytical Comparison ◽  
Classical Models ◽  
Nonlinear Damped Wave Equations ◽  
Theoretical Results ◽  
Consistent Initial Data

This work is concerned with the study of fundamental models from nonlinear acoustics. In Part I, a hierarchy of nonlinear damped wave equations arising in the description of sound propagation in thermoviscous fluids is deduced. In particular, a rigorous justification of two classical models, the Kuznetsov and Westervelt equations, retained as limiting systems for vanishing thermal conductivity and consistent initial data, is given. Numerical comparisons that confirm and complement the theoretical results are provided in Part II.

Remarks on nonlinear elastic waves with null conditions

2020 ◽  
Vol 26 ◽  
pp. 121
Author(s):  
Dongbing Zha ◽  
Weimin Peng
Keyword(s):  
Initial Data ◽  
Global Existence ◽  
Elastic Waves ◽  
Wave Equations ◽  
Alternative Proof ◽  
Classical Solutions ◽  
Small Initial Data ◽  
Hyperelastic Materials ◽  
Variational Structure ◽  
Nonlinear Elastic

For the Cauchy problem of nonlinear elastic wave equations for 3D isotropic, homogeneous and hyperelastic materials with null conditions, global existence of classical solutions with small initial data was proved in R. Agemi (Invent. Math. 142 (2000) 225–250) and T. C. Sideris (Ann. Math. 151 (2000) 849–874) independently. In this paper, we will give some remarks and an alternative proof for it. First, we give the explicit variational structure of nonlinear elastic waves. Thus we can identify whether materials satisfy the null condition by checking the stored energy function directly. Furthermore, by some careful analyses on the nonlinear structure, we show that the Helmholtz projection, which is usually considered to be ill-suited for nonlinear analysis, can be in fact used to show the global existence result. We also improve the amount of Sobolev regularity of initial data, which seems optimal in the framework of classical solutions.

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