与堵塞（Jamming）的接近度控制阻尼颗粒堆积中的声学衰减
Proximity to Jamming Governs Acoustic Attenuation in Damped Packings
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中文总结 AI 辅助
研究人员提出堵塞网络散射（JNS）框架，通过数值模拟揭示流体饱和颗粒介质中声学衰减的线性频率依赖性源于颗粒堆积的临界频率转变，相关特征与实验数据吻合。
中文摘要 AI 辅助
我们采用基于颗粒的数值模拟，解决关于流体饱和颗粒介质中衰减的线性频率依赖性起源这一长期存在的问题。我们研究阻尼无序颗粒堆积中的声学模式与波传播，计算堆积的阻尼振动模式随频率、压力及颗粒接触耗散的变化。这些模式的空间结构与耗散在压力依赖的临界频率处呈现清晰转变：从类粘性连续体行为转变为更局域化的散射模式。我们还测量波速与空间衰减率对相同参数的依赖关系。在同一临界频率下，波传播也从相干运动（此时衰减与频率呈二次方关系、与接触阻尼呈线性关系）转变为更不相干的颗粒尺度运动（此时衰减与频率呈线性关系、与接触阻尼呈亚线性关系）。包括转变频率在内的所有这些特征，均与大量实验数据一致，而此前基于颗粒尺度物理的任何框架均无法解释这些数据。我们将该方法称为“堵塞网络散射（JNS）”，并提出其作为理解流体饱和颗粒介质声学的颗粒尺度框架。
英文摘要
We use particle-based numerical simulations to address a longstanding question regarding the origins of the linear frequency dependence of attenuation in fluid-saturated granular media. We study both the acoustic modes and wave propagation in damped, disordered particle packings. We calculate the damped vibrational modes of packings as a function of frequency, pressure, and grain-contact dissipation. The spatial structure and dissipation of these modes show a clear transition at a pressure-dependent critical frequency from viscous-like continuum behavior to more localized, scattering modes. We also measure how wavespeed and spatial attenuation rate depend on these same parameters. At the same critical frequency, wave propagation also shifts from coherent motion, where attenuation scales quadratically with frequency and linearly with contact damping, to much more incoherent particle-scale motion, where attenuation scales linearly with frequency and sublinearly with contact damping. All of these features, including the transition frequency, are consistent with a large collection of experimental data, which has not been explained by any framework based on grain-scale physics. We refer to this approach as ``Jammed-Network Scattering'' (JNS), and propose it as a grain-scale framework for understanding the acoustics of fluid-saturated granular media.
