Diffusing acoustic wave spectroscopy
Diffusing acoustic wave spectroscopy
复制标题
扩散声波谱
DOI：
10.1103/physreve.65.066605
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发表时间：
2002
影响因子：
2.4
通讯作者：
D. Weitz
中科院分区：
文献类型：
--
作者：
M. L. Cowan;I. Jones;J. Page;D. Weitz
~ 2001年12月5日收到；2002年6月12日出版！我们开发了一种超声相关波谱技术，称为扩散声波波谱技术。在这种技术中，散射体的运动(例如：粒子或夹杂物！是由多重散射声的时间波动决定的。在DAWS中，多次散射声的传播使用扩散近似来描述，这使得时间场波动的自相关函数与多次散射介质的动力学相关。推导了时间场自相关函数与散射体运动的关系式，重点讨论了声学测量中最可能遇到的相关运动类型。该技术的力量用流态化颗粒悬浮液的超声波数据来说明，其中DAWS提供了在广泛的时间和长度范围内悬浮颗粒的局部相对速度和应变率的敏感测量。此外，当结合动态声散射测量粒子的均方根速度时，我们发现DAWS可以用于确定粒子速度相关的空间范围，从而间接测量粒子速度相关函数。从非均匀材料动力学的超声无损评价到地震学中介观现象的地球物理研究，扩散声波光谱的潜在应用是非常广泛的。
~Received 5 December 2001; published 12 June 2002! We have developed a technique in ultrasonic correlation spectroscopy called diffusing acoustic wave spectroscopy ~DAWS!. In this technique, the motion of the scatterers ~e.g., particles or inclusions ! is determined from the temporal fluctuations of multiply scattered sound. In DAWS, the propagation of multiply scattered sound is described using the diffusion approximation, which allows the autocorrelation function of the temporal field fluctuations to be related to the dynamics of the multiply scattering medium. The expressions relating the temporal field autocorrelation function to the motion of the scatterers are derived, focusing on the types of correlated motions that are most likely to be encountered in acoustic measurements. The power of this technique is illustrated with ultrasonic data on fluidized suspensions of particles, where DAWS provides a sensitive measure of the local relative velocity and strain rate of the suspended particles over a wide range of time and length scales. In addition, when combined with the measurements of the rms velocity of the particles using dynamic sound scattering, we show that DAWS can be used to determine the spatial extent of the correlations in the particle velocities, thus indirectly measuring the particle velocity correlation function. Potential applications of diffusing acoustic wave spectroscopy are quite far reaching, ranging from the ultrasonic nondestructive evaluation of the dynamics of inhomogeneous materials to geophysical studies of mesoscopic phenomena in seismology.