Abstract

Suspensions are often found in nature and in technological processes. Suspension particles can differ in density and compressibility from the parent medium and affect the speed and attenuation of sound. It is thought that particle suspensions with neutral buoyancy, i.e., the average density and compressibility of which do not differ from the parameters of the surrounding fluid, do not affect sound propagation. However, if a particle’s center of mass is displaced, i.e., it does not coincide with the point of the Archimedes force, in an acoustic field, such a particle executes rotational oscillations. Rotational oscillations are accompanied by viscous friction and lead to loss of acoustic wave energy. A particle’s center of mass can be displaced by a nonuniform density distribution of a body or a point uneven mass on its surface, which in the general case can be both positive and negative (a cavity). The article analyzes sound propagation in suspensions of rod- and disk-shaped particles characteristic of many media. The formulas describing acoustic wave energy losses in a particle suspension are obtained, and the magnitude of additional sound wave attenuation is estimated, which show that this mechanism can lead to appreciable attenuation.

中文翻译：

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具有旋转自由度的颗粒悬浮液中的声音传播

摘要

悬浮液通常存在于自然界和技术过程中。悬浮颗粒的密度和可压缩性与母体介质可能不同，并且会影响声音的速度和衰减。认为具有中性浮力的颗粒悬浮液，即其平均密度和可压缩性与周围流体的参数没有差异，不会影响声音的传播。但是，如果粒子的质心发生位移，即与阿基米德力的点不重合，则在声场中，此类粒子将执行旋转振荡。旋转振荡会伴随粘滞摩擦并导致声波能量损失。粒子的质心可能由于物体的密度分布不​​均匀或物体表面的点不均匀质量而发生位移，通常情况下，它既可以是正的，也可以是负的（空腔）。该文章分析了许多介质特有的棒状和盘状颗粒悬浮液中的声音传播。得到了描述颗粒悬浮液中声波能量损失的公式，并估计了附加声波衰减的幅度，表明该机制可以导致相当大的衰减。