Pavlic Alen, Nagpure Pushkin, Ermanni Lorenzo, Dual Jürg
Institute for Mechanical Systems, ETH Zurich, 8092 Zurich, Switzerland.
Phys Rev E. 2022 Jul;106(1-2):015105. doi: 10.1103/PhysRevE.106.015105.
In view of its influence on the acoustic radiation force, we investigate the microstreaming around a small solid elastic particle in an ultrasonic standing wave in dependence of its material properties and shape. The configuration is axisymmetric, making it accessible to numerical methods, such as the finite element method. The results reveal a transition from viscous scattering- to microstreaming-dominated acoustic radiation force that depends on the particle density. When a deviation of the particle shape from a sphere becomes smaller than the viscous boundary layer thickness, we show that the influence of the shape on the viscous contributions to the acoustic radiation force diminishes, allowing the use of theoretical models for a spherical particle. However, extreme asymmetric shape perturbations, such as crowns with sharp edges, can give rise to noticeable viscous contributions for a dense particle that is larger than the viscous boundary layer thickness. We also introduce a hybrid analytical model for the acoustic radiation force on a spherical particle that accounts for the microstreaming and particle compressibility and shows a good agreement with numerical simulations for an arbitrary particle size and density.
鉴于其对声辐射力的影响，我们研究了超声驻波中小的固体弹性粒子周围的微流，该微流取决于粒子的材料特性和形状。该结构是轴对称的，这使得诸如有限元法等数值方法能够对其进行研究。结果揭示了从粘性散射主导到微流主导的声辐射力的转变，这取决于粒子密度。当粒子形状与球体的偏差小于粘性边界层厚度时，我们表明形状对声辐射力粘性贡献的影响减小，从而可以使用球形粒子的理论模型。然而，极端的不对称形状扰动，如带有尖锐边缘的冠状物，对于大于粘性边界层厚度的致密粒子，会产生明显的粘性贡献。我们还引入了一个关于球形粒子声辐射力的混合解析模型，该模型考虑了微流和粒子可压缩性，并且与任意粒径和密度的数值模拟结果吻合良好。
