Numerical modeling of the sound field interference pattern in the presence of intense internal waves

Abstract

The purpose of the paper is numerical modeling of the sound field in the presence of intense internal waves to study the interference pattern in inhomogeneous ocean waveguide. It is assumed that intense internal waves are the reason for the sound field modes coupling and horizontal refraction. The results of sound field modeling are processed to obtain acoustic intensity distributions in the frequency-time domain (interferogram) for unmoving sources. The two-dimensional Fourier transform (2D-FT) is applied to analyze the interferogram. The result of the 2D-FT can be called the Fourier-hologram (hologram). The hologram allows us to coherently accumulate the sound intensity of the interferogram in the narrow area as focal spots. It is demonstrated in the paper that the position of focal spots in the hologram depends on the distance between the source and the receiver. The relationship between the interferogram and hologram structures and the unperturbed and scattered fields parameters is obtained in the paper. The hologram spectral density consists of the two disjoint regions corresponding to the scattered and scattered fields. The filtering of these areas allows us to transmit the non-distorted information through an inhomogeneous ocean environment. The numerical simulation results of interferograms and holograms in the presence of the internal waves are considered. [This research was supported by the RFBR (19-29-06075, 19-38-90326).]