Acoustic radiation torque of a cylindrical quasi-Gauss beam on a viscoelastic cylindrical shell near an impedance boundary

• Published in: Wave motion 2022-06, Vol.112, p.102954, Article 102954
• Main Authors: Zang, Yuchen, Wang, Xiangda, Zheng, Yinfei, Su, Chang, Lin, Weijun
• Format: Article
• Language: English
• Subjects: Acoustic impedance; Acoustic radiation torque; Addition theorem; Beam waist position; Cylindrical quasi-Gauss beam; Cylindrical shells; Fluid dynamics; Gaussian beams (optics); Ideal fluids; Impedance boundary; Numerical analysis; Polyethylenes; Radiation; Series expansion; Sound waves; Torque; Viscoelastic cylindrical shell; Viscoelasticity
• ISSN: 0165-2125; 1878-433X
• DOI: 10.1016/j.wavemoti.2022.102954

This work presents a comprehensive analytical formalism to calculate the acoustic radiation torque acting on a viscoelastic cylindrical shell near an impedance boundary, which is exerted by a cylindrical quasi-Gauss beam with an arbitrary incident angle propagating in an ideal fluid. An analytical expression in finite series form for the acoustic radiation torque is derived by applying the partial-wave series expansion method, the image theory and the translational addition theorem. Numerical computations for a viscoelastic cylindrical polyethylene shell immersed in water are provided, with particular emphasis on the effects of the reflecting coefficient of the interface, the shell-boundary distance, the position of the shell, the incident angle and the beam waist. Changing the relative thickness and the interior fluid medium are also considered. It is shown that the cylindrical shell can be rotated counter-clockwise or clockwise, depending on the beam frequency, the shell size, the reflecting coefficient and the incident angle. The periodical oscillation of acoustic radiation torque is also observed as the shell moves away from the boundary. The results of this study can improve our understanding of the acoustic radiation torque behaviors for viscoelastic particles near the boundary, which is commonly encountered in biomedical ultrasound and fluid dynamics. •Radiation torque is derived for an off-axis cylindrical shell near the boundary.•Cylindrical shell can be rotated clockwise or counter-clockwise.•Radiation torque oscillates periodically along with the shell-boundary distance.•Radiation torque peaks correspond to different resonance scattering modes.