Acoustic radiation force on small particle studied via the FDTD method

We report a numerical algorithm combining the finite difference time-domain (FDTD) method with momentum-flux tensor to calculating the acoustic radiation force exerting on small particle. The method is based on propagating the stress and velocity fields through the grid and determining the energy flow with and without the particle. Excellent agreement between the FDTD simulations and scattering wave methods are obtained. As the sizes of the relating particles are smaller than or comparable to wavelength, the algorithm presented here can be easily extended to 3-D and include torque computation algorithms, thus providing a highly flexible and universally useable computation engine.