Reflection and transmission of narrow beams at a water/bottom interface

Abstract

The reflection and transmission of narrow sound beams at the interface between two fluid media was studied experimentally by Muir et al. Sound Vib. 64, 539–551 (1979)] who found that narrow beams impinging on a sedimentary bottom at grazing angles below the critical angle will not be totally reflected as predicted by Snell's law. Here a numerical model yielding an exact solution to the wave equation in horizontally stratified environments is used to analyze the observed phenomenon. A beam of any realistic width is generated by introducing a vertical source array and properly phasing the single sources. It is shown that the deviation from Snell's law is due to the finite width of the angular spectrum of narrow beams, and the results given are in good qualitative agreement with the experimental results.