Measurement of acoustic radiation force on a sphere near a boundary

Presented here are results from an experiment designed to measure the acoustic radiation force on a sphere near a planar boundary. The experiment was conducted with a sound beam incident on a polypropylene sphere in water. Results were obtained for the sphere in a free field as well as near a soft foam surface. The radiation force was measured by forming a pendulum with the sphere and tracking its displacement with video recordings. The effect of the boundary is demonstrated by examining the ratio of the radiation force measured with and without the boundary, and by examining the radiation force measured as a function of distance between the sphere and the boundary. Measurements are compared with an existing analytical model for radiation force on a sphere near a boundary [Simon and Hamilton, J. Acoust. Soc. Am. 153, 627– 642 (2023)].