Focusing and Refraction of Harmonic Sound and Transient Pulses in Stratified Media
Focusing and Refraction of Harmonic Sound and Transient Pulses in Stratified Media
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分层介质中谐波和瞬态脉冲的聚焦和折射
DOI：
10.1121/1.1912423
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发表时间：
1971
影响因子：
2.4
通讯作者：
A. Silbiger
中科院分区：
文献类型：
--
作者：
D. Sachs;A. Silbiger
在声速取决于位置的介质中，传播的声音将被折射，并且在某些情况下被聚焦。在聚焦区域，通常被称为焦散或收敛区，已观察到的压力水平的显着放大以上的预测球形扩展连续波以及爆炸脉冲。此外，爆炸脉冲的波形经历剧烈的畸变。本文提出了一个点声源在分层媒质中折射和聚焦的渐近理论。它适用于现实的速度剖面，包括瞬态脉冲和谐波。与Barash和Goertner最近涉及爆炸脉冲的实验的比较表明，该理论给出了焦散线处峰值压力水平的可靠估计，但仅定性地再现了聚焦脉冲的形状。这种差异主要归因于理论公式中忽略了有限振幅效应。在理论中采用的高频渐近方法固有的不准确性进行了详细讨论。
In media for which the speed of sound is position dependent, propagating sound will be refracted and, in some cases, focused. In the focusing regions, usually referred to as caustics or convergence zones, significant amplification of the pressure levels above those predicted by spherical spreading has been observed for continuous waves as well as for explosive pulses. In addition, the waveforms of explosive pulses undergo drastic distortion. In the present paper, an asymptotic theory of the refraction and focusing of sound originating from a point source in a stratified medium is presented. It is applicable to realistic velocity profiles and encompasses both transient pulses and harmonic waves. A comparison with Barash's and Goertner's recent experiment involving explosive pulses indicates that the theory gives reliable estimates of the peak pressure levels at caustics, but reproduces only qualitatively the shape of the focused pulse. The discrepancy is attributed mainly to the neglect of finite‐amplitude effects in the theory's formulation. The inaccuracies inherent in the high‐frequency asymptotic methods employed in the theory are discussed in some detail.