The existence of Stoneley waves as a loss mechanism in plane wave reflection problems

Abstract

In a previous paper [’’Influence of Stoneley waves on plane-wave reflection coefficients: Characteristics of bottom reflection loss,’’ K. E. Hawker, J. Acoust. Soc. Am. 64, 548 (1978)] it was shown that for certain configurations of layered fluids overlying a rigid (solid) substrate, the reflection loss would display narrow peaks of significant amplitude. It was suggested in that paper that these peaks were due to excitation of Stoneley waves at the fluid–solid interface. In the present paper this association is made more precise and definite. Through an extension of the classical theory of Stoneley waves to the case of inhomogeneous media, it is shown that the angles at which the reflection-loss peaks occur are precisely those angles for which the horizontal component of phase velocity in the fluid equals the Stoneley wave phase velocity. In addition, the near independence of the reflection loss peaks on frequency is explained quantitatively.