Computed horizontal time-reversing array retrofocusing in a dynamic shallow-water sound channel

Abstract

A time-reversing array (TRA) can retrofocus acoustic energy to the location of its original source even when the acoustic environment is complex and unknown. Previous computational and experimental studies have utilized a vertical TRA to determine performance in shallow-water sound channels. However, other TRA deployment configuration possibilities exist. Here, results, based on narrow-band computations made with a parabolic equation code (ram by M.D. Collins), are presented for a horizontal array in various orientations with respect to the source. In addition to characterizing the influence of range, acoustic frequency, and horizontal-TRA orientation on the quality of the retrofocus, the sensitivity of horizontal-TRA retrofocusing to internal wave dynamics in the water column of a shallow-water sound channel is also shown. The internal wave model is based on a superposition of linear internal waves whose temporal spectrum has been matched to spectra measured during the SWARM ’95 experiment. Some performance differences are noted between end-fire and broadside array–source orientations. If time allows, results from fully 3D simulations will be shown. [Work supported by ONR, Ocean Acoustics.]