Sonic Boom Excited Sediment Waves: A Model Study

H.K. Cheng, J.A. Kunc, J.R. Edwards

Abstract


Sonic boom excited sediment waves are investigated with a model of interacting wave fields comprising water of finite depth and an elastic medium representing the sediment. The latter is assumed to be uniform, isotropic and semi-infinite in extent. The free modes are found to be dispersive, resulting in a finite (non-vanishing) resonance speed range. The study recognizes the difference in the far-field behavior between the excited resonance mode and the wave group of free modes: whereas the excited underwater wave of the resonance mode propagates at the same speed as the sonic-boom air load and remains in the form of a monochromatic wave train, the wave group of the free modes disperses into a wave packet and attenuate with increasing distance and time. Examples of a sediment model of fine sand with sonic boom waves at two flight Mach numbers are discussed. Differences and similarities between the present analysis and Desharnais and Chapman's study are noted.

Keywords


Acoustic fields; Acoustic wave propagation; Arrays; Computational methods; Computer simulation; Elastic moduli; Hydrophones; Numerical analysis; Problem solving; Resonance; Sediments; Underwater acoustics; Waveform analysis; Sediment waves; Wave fields

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