Acoustic radiation torque exerted on a subwavelength spheroidal particle by a traveling and standing plane wave

Abstract

The nonlinear interaction of ultrasonic waves with a nonspherical particle may give rise to the acoustic radiation torque on the particle. This phenomenon is investigated here considering a rigid prolate spheroidal particle of subwavelength dimensions that is much smaller than the wavelength. Using the partial wave expansion in spheroidal coordinates, the radiation torque of a traveling and standing plane wave with arbitrary orientation is exactly derived in the dipole approximation. We obtain asymptotic expressions of the torque as the particle geometry approaches a sphere and a straight line. As the particle is trapped in a pressure node of a standing plane wave, its radiation torque equals that of a traveling plane wave. We also find how the torque changes with the particle aspect ratio. Our findings are in excellent agreement with previous numerical computations. Also, by analyzing the torque potential energy, we determine the stable and unstable spatial configuration available for a particle.

arXiv comment6 pages, 3 figures

References in corpus (3)

• Acoustic radiation force and torque on an absorbing compressible particle in an inviscid fluid
• Acoustic interaction forces and torques acting on suspended spheres in an ideal fluid
• T-matrix evaluation of three-dimensional acoustic radiation forces on nonspherical objects in Bessel beams with arbitrary order and location

Cited by in corpus (6)

• Nonlinear interaction of acoustic waves with a spheroidal particle: radiation force and torque effects
• An efficient procedure to predict the acoustophoresis of axisymmetric irregular particles above ultrasound transducer array
• Mean-acoustic fields exerted on a subwavelength axisymmetric particle
• Acoustic radiation force and radiation torque beyond particles: Effects of non-spherical shape and Willis coupling
• Acoustic Lateral Recoil Force and Stable Lift of Anisotropic Particles
• Acoustic radiation force and torque on spheroidal particles in an ideal cylindrical chamber