Linear and nonlinear propagation of a pulsed sound beam in a dissipative fluid

Abstract

Linear and nonlinear propagation of pulsed sound beams is considered. The combined effects of diffraction, absorption, and nonlineartry are discussed within the linear and the weakly nonlinear (quasilinear) approximation of the Khokhlov‐Zabolotskaya‐Kuznetsov nonlinear parabolic equation. For the special case of a Gaussian on‐source amplitude distribution, short pulses can be followed all the way from the sound source and into the dissipative far field, both within a linear and a weakly nonlinear model. The results obtained are related to the theory of scattering of sound by sound [Berntsen et al., J. Acoust. Soc. Am. 86, 1968–1983 (1989)], and to the self‐demodulation of transient carriers [H. O. Berktay, J. Sound Vib. 2, 435–461 (1965)]. [Work supported by the Norwegian Research Council for Science and Humanities.]