Coherent acoustic response of a screen containing a random distribution of scatterers: Comparison between different approaches
Coherent acoustic response of a screen containing a random distribution of scatterers: Comparison between different approaches
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包含随机分布的散射体的屏幕的相干声响应：不同方法之间的比较
DOI：
10.1088/1742-6596/269/1/012004
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
A. Shuvalov
中科院分区：
文献类型：
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作者：
J. Dubois;C. Aristégui;O. Poncelet;A. Shuvalov
液体中悬浮液和气泡群的超声研究的理论模型通常依赖于相干波响应的概念，其中给定的介质被视为有效的均匀介质。更具体地说，相干响应可以通过有效波数和有效阻抗以简单的方式公式化。这些又可以通过给定散射介质的实际材料特性来表示。有效波数和阻抗的推导是多次散射理论中存在的许多不同方法的问题。本文研究了声波入射到流体中随机分布的圆柱形夹杂物屏上的相干响应。反射和透射系数通过有效波数和阻抗来表示，有效波数和阻抗由Foldy、Waterman & Truell和林顿& Martin三种不同的模型提供。所获得的表达式进行了分析，以阐明这些方法之间的定量差异是什么，揭示了在相干响应，以及这种差异如何取决于基本参数的问题，如频率，散射体的浓度和它们的对比度相对于流体矩阵。本工作的另一个方面是将上述分析结果与数值数据进行比较。它已经获得了一个确定性的计算代码，提供了通过平均的散射体的位置的各种采样的输出的相干波场的装置。知道这个数值基准，使我们能够指定的有效域的研究中的三个分析方法。
Theoretical models underlying the ultrasonic study of suspensions and bubble swarms in liquids often rely on the concept of a coherent wave response, within which the given medium is viewed as an effective homogeneous medium. More specifically, the coherent response can be formulated in a straightforward manner via the effective wave number and the effective impedance. These in turn can be expressed through the actual material properties of the given scattering medium. The derivation of the effective wave number and impedance is the issue of a number of different approaches existing in the multiple-scattering theory. The present work deals with a coherent response of acoustic wave impinging on a screen of cylindrical inclusions randomly distributed in a fluid. The reflection and transmission coefficients have been expressed via the effective wave number and impedance that are provided by three different models due to Foldy, Waterman & Truell, and Linton & Martin. The obtained expressions have been analyzed with a view to illuminate what is the quantitative difference between those approaches as revealed in the coherent response, and how this difference depends on the basic parameters of the problem such as the frequency, the concentration of scatterers and their contrast relatively to the fluid matrix. Another aspect of this work is to compare the above analytical results with the numerical data. It has been obtained by means of a deterministic computational code which delivers the coherent wave field through averaging the outputs for various samplings of the positions of scatterers. Knowing this numerical benchmark allows us to specify the validity domains for each of the three analytical methods under study.