高斯波束对界面附近离轴球形粒子的轴向声辐射力

从声波的散射理论出发，利用级数展开法得到高斯波束的波束因子，推导其对阻抗边界下离轴球形粒子声辐射力.针对刚性球与液体球两种球形粒子进行数值模拟，与自由空间的情况进行比较.讨论边界反射系数、粒子与边界距离、束腰半径以及离轴角度与距离等对声辐射力的影响.仿真结果表明：边界反射系数的增大会引起声辐射力的增加，但不改变峰值的位置；在合适的频率处，可以产生负向声辐射力；声辐射力随粒子与边界距离呈周期性变化；束腰半径的影响主要体现在中高频；随着粒子偏离传播轴的距离和角度增大，声辐射力明显衰减.该研究为利用高斯波束实现对粒子的操纵提供理论基础.

Axial Acoustic Radiation Force of Gaussian Beam Incident on an Off-axis Spherical Particle Near Boundary

Based on scattering theory of sound waves, beam factor of a Gaussian beam is obtained with series expanding theory. Analytical expression of acoustic radiation force on a spherical particle near an impedance boundary is deduced. Numerical simulations of rigid and fluid particles are carried out and comparison with those in free space is made. Effects of reflecting coefficient, distance between particle and boundary and waist radius on acoustic radiation force are discussed. It shows that the acoustic radiation force increases along with reflecting coefficient of the boundary, while the peaks are not changed. At some appropriate frequencies, negative acoustic radiation force can be obtained. The acoustic radiation force changes periodically with the distance between particle and boundary. Moreover, the waist radius mainly affects acoustic radiation force at middle and high frequencies. As the particle off-axis distance and angle deviation increases, attenuation of acoustic radiation force becomes obvious. This work provides a theoretical basis for particle manipulation using Gaussian beam.