The average transmitted wave in random particulate materials
The average transmitted wave in random particulate materials
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DOI：
10.1088/1367-2630/ad49c2
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发表时间：
2023-08
影响因子：
3.3
通讯作者：
Aris Karnezis;P. S. Piva;A. Gower
中科院分区：
文献类型：
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作者：
Aris Karnezis;P. S. Piva;A. Gower
微波遥感在穿过云层或密集的冰层时会发生显著的变化。这种现象并不是微波所独有的;例如，超声波在穿过异质组织时也会受到干扰。了解粒子填充环境中的平均传输对于改进数据提取甚至创建可以选择性地阻挡或吸收某些波频率的材料至关重要。大多数计算平均透射场的方法都假设它满足具有复有效波数的波动方程。然而，最近的理论工作已经预测了一个以上的有效波传播，甚至在材料是统计各向同性和标量波。在这项工作中，我们提供了第一个明确的证据，这些预测的多个有效波，使用高保真蒙特-卡罗模拟，不作任何统计假设。为了实现这一点，有必要填补颗粒材料理论中的一个缺失环节：我们证明入射波不会在材料中传播，这通常被视为称为Ewald-Oseen消光定理的假设。通过证明这一点，我们可以得出结论，消光长度（入射波被消光所需的距离）等于粒子之间的相关长度。
Microwave remote sensing is significantly altered when passing through clouds or dense ice. This phenomenon is not unique to microwaves; for instance, ultrasound is also disrupted when traversing through heterogeneous tissues. Understanding the average transmission in particle-filled environments is central to improve data extraction or even to create materials that can selectively block or absorb certain wave frequencies. Most methods that calculate the average transmitted field assume that it satisfies a wave equation with a complex effective wavenumber. However, recent theoretical work has predicted more than one effective wave propagating even in a material which is statistically isotropic and for scalar waves. In this work we provide the first clear evidence of these predicted multiple effective waves by using high-fidelity Monte-Carlo simulations that do not make any statistical assumptions. To achieve this, it was necessary to fill in a missing link in the theory for particulate materials: we prove that the incident wave does not propagate within the material, which is usually taken as an assumption called the Ewald–Oseen extinction theorem. By proving this we conclude that the extinction length—the distance it takes for the incident wave to be extinct—is equal to the correlation length between the particles.