Garbin Alexander, Leibacher Ivo, Hahn Philipp, Le Ferrand Hortense, Studart André, Dual Jürg
Institute of Mechanical Systems (IMES), Department of Mechanical and Process Engineering, Swiss Federal Institute of Technology (ETH Zurich), Tannenstrasse 3, CH-8092 Zurich, Switzerland.
Complex Materials, Department of Materials, Swiss Federal Institute of Technology (ETH Zurich), Vladimir-Prelog-Weg 5, CH-8093 Zurich, Switzerland.
J Acoust Soc Am. 2015 Nov;138(5):2759-69. doi: 10.1121/1.4932589.
Disk-shaped microparticles experience an acoustic radiation force and torque in an ultrasonic standing wave. Hence, they are translated by the acoustic field, an effect called acoustophoresis, and rotated. The torque effect is also known from the "Rayleigh disk" which is described in literature for sound intensity measurements. In this paper, inviscid numerical simulations of acoustic radiation forces and torques for disks with radius ≪ wavelength in water are developed in good agreement with former analytical solutions, and the dependence on disk geometry, density, and orientation is discussed. Experiments with alumina disks (diameter 7.5 μm), suspended in an aqueous liquid in a silicon microchannel, confirm the theoretical results qualitatively at the microscale and ultrasonic frequencies around 2 MHz. These results can potentially be applied for the synthesis of disk-reinforced composite materials. The insights are also relevant for the acoustic handling of various disk-shaped particles, such as red blood cells.
盘状微粒在超声驻波中会受到声辐射力和扭矩。因此，它们会被声场平移，这种效应称为声泳，并且会发生旋转。扭矩效应在“瑞利盘”中也有记载，文献中曾用它来进行声强测量。本文针对水中半径远小于波长的圆盘，开展了声辐射力和扭矩的无粘数值模拟，模拟结果与先前的解析解高度吻合，并讨论了其对圆盘几何形状、密度和取向的依赖性。在硅微通道中将氧化铝圆盘（直径7.5μm）悬浮于水性液体中进行实验，在微观尺度和2MHz左右的超声频率下定性地证实了理论结果。这些结果有可能应用于盘状增强复合材料的合成。这些见解对于各种盘状颗粒（如红细胞）的声学操控也具有重要意义。
