2023_programme: Numerical simulation of broadband acoustic signal propagation in a shallow-water waveguide with an inhomogeneous bottom structure

• Session: 07. Modeling techniques for underwater acoustic scattering and propagation (including 3D effects)
  Organiser(s): Boris Katsnelson and Pavel S. Petrov
• Lecture: Numerical simulation of broadband acoustic signal propagation in a shallow-water waveguide with an inhomogeneous bottom structure [invited]
  Paper ID: 1941
  Author(s): Sidorov Danila, Lunkov Andrey, Petnikov Valery
  Presenter: Sidorov Danila
  Abstract: Numerical simulation is applied to study a broadband acoustic field, formed by a point source, emitting signals in the frequency range 50 to 1000 Hz in the shelf area with a 3-D inhomogeneous bottom structure. As a model of inhomogeneous waveguide, a transitional zone between acoustically soft and acoustically hard bottom is considered. The waveguide depth is constant and equals 30 m. The acoustic tracks are oriented either along or across the boundary between two types of bottoms. Normal mode theory and parabolic equations are used to study the effects of horizontal refraction and mode coupling. Numerical experiments show that the horizontal refraction is sufficient in case of low frequency (below 100 Hz). It leads to increasing sound pressure level and time arrival delay of an acoustic pulse that propagates along the transitional zone. The level increase is up to 65 dB in comparison with Nx2-D approximation. Mode coupling effect is dominating at frequencies 100 to 1000 Hz, in the across direction. It appears in quasi-periodic oscillations of modal amplitude in the frequency domain. The conclusions from the simplified model are verified in simulations for a realistic seabed structure in the Kara Sea.
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• Corresponding author: Mr Danila Sidorov
  Affiliation: Prokhorov General Physics Institute of the Russian Academy of Sciences
  Country: Russian Federation
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