Clark Abram H, Olson Derek R, Swartz Andrew J, Starnes W Mason
Physics Department, Naval Postgraduate School, Monterey, California 99343, USA.
Oceanography Department, Naval Postgraduate School, Monterey, California 99343, USA.
J Acoust Soc Am. 2024 May 1;155(5):3537-3548. doi: 10.1121/10.0026126.
Here, we theoretically and computationally study the frequency dependence of phase speed and attenuation for marine sediments from the perspective of granular mechanics. We leverage recent theoretical insights from the granular physics community as well as discrete-element method simulations, where the granular material is treated as a packing of discrete objects that interact via pairwise forces. These pairwise forces include both repulsive contact forces as well as dissipative terms, which may include losses from the fluid as well as losses from inelasticity at grain-grain contacts. We show that the structure of disordered granular packings leads to anomalous scaling laws for frequency-dependent phase speed and attenuation that do not follow from a continuum treatment. Our results demonstrate that granular packing structure, which is not explicitly considered in existing models, may play a crucial role in a complete theory of sediment acoustics. While this simple approach does not explicitly treat sound propagation or inertial effects in the interstitial fluid, it provides a starting point for future models that include these and other more complex features.
在此，我们从颗粒力学的角度对海洋沉积物相速度和衰减的频率依赖性进行了理论和计算研究。我们利用了颗粒物理学界最近的理论见解以及离散元方法模拟，其中颗粒材料被视为通过成对力相互作用的离散物体的堆积。这些成对力既包括排斥接触力，也包括耗散项，耗散项可能包括流体造成的损失以及颗粒间接触处非弹性造成的损失。我们表明，无序颗粒堆积的结构导致了频率依赖性相速度和衰减的反常标度律，这并非连续介质处理所能得出的。我们的结果表明，现有模型中未明确考虑的颗粒堆积结构，可能在沉积物声学的完整理论中起着关键作用。虽然这种简单方法没有明确处理间隙流体中的声传播或惯性效应，但它为未来包含这些及其他更复杂特征的模型提供了一个起点。
