Numerical Computation of Time-Averaged Acoustic Radiation Force on Arbitrarily Shaped Particles Using an Improved Immersed Boundary Method

Abstract

This work focuses on the numerical computations of the second-order time-averaged acoustic radiation force on solid particles with complex geometries based on the perturbation theory and linear scattering approximation. The acoustic field scattered by arbitrarily shaped particles immersed in inviscid fluid is computed using the finite-difference time-domain method with a fourth-order dispersion-relation-preserving scheme, which serves as the basis for radiation force calculation. The infinite fluid domain is truncated into a finite computational domain by defining perfectly matched layers at computational boundaries. A meticulous immersed boundary method is developed to represent the interface between an irregularly shaped solid and the Cartesian computational grid, improving the precision of the computed acoustic radiation force. Based on the proposed method, the acoustic radiation force acting on a rigid elliptical cylinder exerted by planar standing acoustic waves is computed first, and the accuracy of the computed results is verified by comparing them with reference solutions obtained using the finite element method. Additionally, the dependences of the computational precision of the acoustic radiation force on some key parameters are assessed, and the criteria for determining the parameter values are developed to avoid the excessive constraint phenomenon which may occur in the numerical results. Finally, numerical examples of computing the acoustic radiation force on solid particles with complex geometries are implemented to check the effectiveness of the proposed numerical method.