Position dependence of the standing-wave radiation pressure quadrupole projection on a sphere applied to drop shape.

There have been decades of interest in using the ultrasonic radiation pressure of standing waves to deform nearly spherical objects. An analytical approach sometimes associated with the present author involves approximating projections of the radiation pressure on spheres small in comparison with the wavelength and calculating the response to that projection. In 1981, for small fluid spheres, some terms in the quadrupole projection were published along with the dependence on the size and location of the sphere.

Contrast factor for standing-wave radiation forces on spheres: Series expansion in powers of sphere radius.

Recently researchers often normalize the radiation force on spheres in standing waves in inviscid fluids using an acoustic contrast factor (typically denoted by Φ) that is independent of kR where k is the wave number and R is the sphere radius. An alternative normalization uses a function Ys that depends on kR. Here, standard results for Φ are extended as a power series in kR using prior Ys results.

Trapping in acoustic standing waves: Effect of liquid drop compressibility.

The Reflections series takes a look back on historical articles from The Journal of the Acoustical Society of America that have had a significant impact on the science and practice of acoustics.

Backscattering by a tilted intermediate thickness cylindrical metal empty shell in water.

Backscattering by metal shells in water was investigated by Morse, Marston, and Kaduchak [J. Acoust Soc. Am.