Nonlinear distortion of the bubble pulse in a layered inhomogeneous ocean

Abstract

Many years ago, the author analyzed a representative deep‐fired long‐range underwater explosion waveform [J. Acoust. Soc. Am. 35, 800 (1963)]. The most striking feature was the so‐called “double shock” formation, e.g., a strong resemblance between the shock wave and bubble pulse in both amplitude and shape. The phenomenon is attributed to the combined effects of detonation depth and waveform propagation. In a previous paper the characteristics of an explosion waveform at the source, as function of shot depth was established [Proc. 11th ICA, Paris (1983), Vol. 1, pp. 345–348]. Weak shock theory was used to study nonlinear distortion of the bubble pulse as it propagates in an homogeneous, unbounded, dissipationless medium [Proc. 10th Int. Symp. Nonlinear Acoust., Kobe, Japan (1984), pp. 79–82]. It was found that the deepest fired shots suffer the greatest distortion but that, in general, extremely long range is required for shock wave formation. However, focusing due to inhomogeneous structure may substantially increase pulse strength thereby enhancing nonlinear effects. Here the effect of inhomogeneous layering on the range required for shock wave formation is investigated.