Lima Everton B, Silva Glauber T
Physical Acoustics Group, Instituto de Física, Universidade Federal de Alagoas, Maceió, Alabama 57072-970, Brazil.
J Acoust Soc Am. 2021 Jul;150(1):376. doi: 10.1121/10.0005625.
The acoustic radiation force produced by ultrasonic waves is the "workhorse" of particle manipulation in acoustofluidics. Nonspherical particles are also subjected to a mean torque known as the acoustic radiation torque. Together they constitute the mean acoustic fields exerted on the particle. Analytical methods alone cannot calculate these fields on arbitrarily shaped particles in actual fluids and are no longer fit for purpose. Here, a semi-analytical approach is introduced for handling subwavelength axisymmetric particles immersed in an isotropic Newtonian fluid. The obtained mean acoustic fields depend on the scattering coefficients that reflect the monopole and dipole modes. These coefficients are determined by numerically solving the scattering problem. Our method is benchmarked by comparison with the exact result for a subwavelength rigid sphere in water. Besides, a more realistic case of a red blood cell immersed in blood plasma under a standing ultrasonic wave is investigated with our methodology.
超声波产生的声辐射力是声流体动力学中粒子操控的“主力军”。非球形粒子还会受到一种称为声辐射扭矩的平均扭矩作用。它们共同构成了作用在粒子上的平均声场。仅靠解析方法无法计算实际流体中任意形状粒子上的这些场，已不再适用。在此，引入一种半解析方法来处理浸没在各向同性牛顿流体中的亚波长轴对称粒子。所得到的平均声场取决于反映单极子和偶极子模式的散射系数。这些系数通过数值求解散射问题来确定。我们的方法通过与水中亚波长刚性球体的精确结果进行比较来进行基准测试。此外，还运用我们的方法研究了在驻波超声作用下浸没在血浆中的红细胞这一更为实际的情况。
