SCATTERING OF SOUND IN SUSPENSIONS OF SPHEROIDALLY SHAPED PARTICLES

Particles are assumed to have oblate and prolate spheroidal, spherical, disklike, and needlelike shapes, with symmetry axes for oblate and prolate spheroids assumed to be either parallel or perpendicular to the acoustic field. The disk-shaped and needle-shaped particles are assumed to be either broadside or edgewise (or end on) to the acoustic field. Scattering cross section for sound propagation in particle suspensions prepared in viscous fluid media has been calculated. For large density differences (of about 150%) between suspension components, computations indicate substantial effects of particle shape and orientation on the scattering of sound in dilute suspensions. For an oblate spheroid oscillating broadside, the backscattered signal is significantly (up to 30%) greater than that for a sphere, or for an oblate spheroid oscillting edgewise. Departures from Rayleigh's law of scattering (by about 10% over one frequency decade) occur for very dense particles suspended in a viscous fluid medium. © 1979, American Association of Physics Teachers. All rights reserved.