Geometric Formation Condition of Internal Wave Attractors and Its Influence on Sound Fields

The condition of the terrain is one of the major causes for the formation of internal wave attractors. These internal wave attractors, which induce a fluctuation of the isothermal surface and may result in a special sound velocity gradient field, usually exist in specific marine environments. To develop a novel communication and concealed way for undersea vehicles, research on the terrain conditions that generate internal wave attractors is necessary. In this study, the geometric constraints of stable internal wave attractors were derived by studying an incompressible viscous salt solution with a two-dimensional gravity field using the finite volume method. According to the relationship between sound velocity and temperature, the influences of internal wave attractors on sound velocity and sound velocity gradient fields were studied by introducing the temperature field control equation. The simulation results showed that, owing to the multiple reflections of the internal waves under a small disturbance, internal wave attractors will appear in a canyon region with a nearly right-angled trapezoidal cross section. When the water surface width and depth ratio of the canyon are in the range of 1 to 1.3, there is a specific trapezoidal section that can contribute a stable internal wave attractor, while the sound velocity gradient field presents a quadrilateral configuration, which can provide a specific communication and concealment site for undersea vehicles.