Acoustic wave front reversal in a three-phase media

TL;DR

This paper investigates acoustic wave front reversal in a three-phase marine sediment containing air bubbles, focusing on nonlinear bubble oscillations and two mechanisms of phase conjugation, with derived equations and amplitude expressions.

Contribution

It introduces a detailed analysis of two distinct mechanisms of acoustic wave front conjugation in a three-phase medium with nonlinear bubble oscillations.

Findings

Identified stimulated Raman-type sound scattering as a phase conjugation mechanism.

Derived nonlinear equations for wave-front conjugation in bubbly sediments.

Compared wave amplitude expressions for different bubble oscillation frequencies.

Abstract

Acoustic wave front conjugation is studied in a sandy marine sediment that contains air bubbles in its fluid fraction. The considered phase conjugation is a four-wave nonlinear parametric sound interaction process caused by nonlinear bubble oscillations which are known to be dominant in acoustic nonlinear interactions in three-phase marine sediments. Two various mechanisms of phase conjugation are studied. One of them is based on the stimulated Raman-type sound scattering on resonance bubble oscillations. The second one is associated with sound interactions with bubble oscillations which frequencies are far from resonance bubble frequencies. Nonlinear equations to solve the wave-front conjugation problem are derived, expressions for acoustic wave amplitudes with a reversed wave front are obtained and compared for various frequencies of the excited bubble oscillations.