Physical Principles of Contemporary Sonics

Abstract

Contemporary sonics embraces a wide variety of applications of sound waves for the acquisition of information and for the production of useful effects in the medium or at its boundaries. Information gathering capitalizes chiefly on linear, small-signal effects such as the time of flight or the direction of return of pulses, the absorption or speed of sound in the medium, or some effect of the medium on a vibrating source. The useful gross effects of sound waves are associated with the production of high local velocities, shear rates, or accelerations, and with the second-order, nonlinear effects that lead to localized streaming, cavitation, and the reduction of concentration gradients by breakdown of laminar or sublaminar boundary layers. A catalog of these effects, with some attention to numerical magnitudes, indicates suggestively the present scope of sonics.