Examples of Two-Wavenumber Spectra in Nonhomogeneous One-Dimensional Structures

摘要

Structures of interest to hydroacoustic research frequently have spatially varying properties which cause the field variable to be statistically nonhomogeneous. Two-wavenumber spectra of one-dimensional nonhomogeneous fields have been defined, but there exists little experience in interpreting these spectra. This paper presents a first look at the two-wavenumber spectra of various theoretical and measured examples of nonhomogeneous fields. The examples were chosen to form a progression of two-wavenumber spectra from simple canonical forms of exponentially damped travelling waves to more complex measured nonhomogeneous fields on axisymmetric periodic structures. The desired two-wavenumber spectra are obtained from calculated or measured cross-spectral density matrices by use of an efficient algorithm. A comparison of the spectra of both the canonical and measured fields display a common structure. One- and two-wavenumber spectra of measured data are compared to illustrate the potential simplification and interpretive role of two-wavenumber spectra. Keywords: Underwater acoustics. (JHD)