Axial and transverse acoustic radiation forces on an elliptical cylinder arbitrarily positioned in a cylindrical quasi-Gaussian beam

A formal analytical solution of the acoustic radiation force on an elliptical cylinder arbitrarily positioned in a cylindrical quasi-Gaussian beam is developed. The scattering coefficients for the elliptical cylinder are obtained through forcing the acoustic field to meet the boundary condition at the surface of the cylinder, which depends on whether the elliptical cylinder is rigid or fluid. A numerical integration is performed for each partial-wave during the computations. Numerical simulations are provided with particular emphases on the amount of the shift from the center of the cylinder, the tilt incident angle, the aspect ratio of the cylinder and the beam waist of the incident beam. The radiation force on a fluid elliptical cylinder shows a more oscillatory behavior than a rigid one. The attractive transverse radiation force exists under certain conditions, proving the feasibility of designing lateral acoustic tweezers. A wider incident beam induces a stronger axial radiation force due to expansion of the cross section. The results are helpful for predicting the dynamic behaviors of cylindrical particles and guiding particle manipulation in the field of focused cylindrical beams.