^{1}, Kian-Meng Lim

^{2}and Fook Siong Chau

^{2}

^{1}Department of Mechanical Engineering, National University of Singapore, Dynamics lab, E1-02-03,

1 Engineering Drive 2, Singapore 117576.

^{2}Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576.

In this study, the acoustic radiation force and moment acting on spheres and ellipsoids were calculated using two numerical schemes: the finite element method and the multipole expansion method. Two geometrical parameters, size and the angle of incidence of the wave, were varied to see their effects on the force and moment calculated. For small sizes, the numerical results were consistent with King’s formula for the spheres and Marston’s formula for ellipsoids. For spheres with large radius, the acoustic radiation force deviates considerably from the analytical solution. Due to its symmetry, the acoustic moment is zero for a sphere, regardless of its size and position inside the channel. The results for oblate ellipsoids show that the acoustic radiation force generally decreases with increase in the angle of incidence of the wave due to the reduced effective cross-sectional area perpendicular to the wave. For ellipsoids, the acoustic moment function has a maximum value at an angle of incidence of 45° for all the cases. The acoustic radiation moment has its maximum value at pressure node for all the incidence angles. Both the finite element and multipole expansion methods are able to give accurate results, especially for large-size objects and complex geometries. The multipole expansion method is an extension of the analytical series solution; therefore, it is more efficient in terms of computational time and resources than the finite element model.