Abstract
Based on the local mode method, the problem of the average intensity (transmission loss) behavior in shallow waveguides with losses in the bottom and fluctuations of the speed of sound in water is considered. It was previously shown that the presence in a waveguide with absorbing penetrable bottom of 2D random inhomogeneities of the speed of sound leads to the appearance of strong fluctuations in the acoustic field already at relatively small distances from the sound source. One of the most important and interesting manifestations of this is the slowing down of the average intensity of the acoustic field compared with a waveguide, which has no such random inhomogeneities of the speed of sound. This paper presents the results of a numerical analysis of the decay of the average field intensity in the presence of both Gaussian and non-Gaussian fluctuations in the speed of sound. It is shown that non-Gaussian fluctuations do not fundamentally change the conclusion about reducing losses during the propagation of a sound signal but can enhance this effect.
Highlights
It is well known that the parameters of natural waveguides, as well as optical, electrodynamic, plasma, dielectric, and other waveguides, to one degree or another, are subject to random variations [1,2]
During the propagation of an acoustic signal in the sea, one of the general sources of fluctuations of the main parameter, that is the speed of sound, is the passage of internal gravity waves (IGW) [3,4,5]
This circumstance is especially significant in the coastal zones of the ocean, where a shallow water waveguide with a thermocline in the water column and a penetrable, absorbing bottom occurs for a low-frequency sound signal
Summary
It is well known that the parameters of natural waveguides (ocean, atmosphere), as well as optical, electrodynamic, plasma, dielectric, and other waveguides, to one degree or another, are subject to random variations [1,2]. During the propagation of an acoustic signal in the sea, one of the general sources of fluctuations of the main parameter, that is the speed of sound, is the passage of internal gravity waves (IGW) [3,4,5]. This circumstance is especially significant in the coastal (shelf) zones of the ocean, where a shallow water waveguide with a thermocline in the water column and a penetrable, absorbing bottom occurs for a low-frequency sound signal. Non-Gaussian fluctuations may even somewhat enhance the previously established effects of attenuation of the decay of the average signal intensity in the waveguide
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