Geometric Formation Condition of Internal Wave Attractors and Its Influence on Sound Fields
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摘要: 特定海洋环境会产生内波吸引子现象, 从而诱导等温面的波动, 形成特殊的声速梯度场。对内波吸引子产生条件进行研究, 对开发新型水下航行器的通信和隐蔽方式具有积极意义。地形条件是引发内波吸引子形成的要素之一。文中基于有限体积法研究了二维重力场作用下不可压缩粘性盐溶液中, 形成稳定内波吸引子的几何约束条件, 并依据声速与温度的关系, 通过引入温度场控制方程, 研究了内波吸引子对声速场和声速梯度场的影响。研究表明, 对于近直角梯形截面的峡谷区域, 当存在微小扰动时, 海洋中会产生内波, 经多次反射后形成内波吸引子; 当峡谷水面宽度和深度比在1~1.3范围内, 存在可形成稳定的内波吸引子特定梯形截面, 同时声速梯度场也呈现出四边形构型, 可为水下航行器提供特定的通信和隐蔽空间。Abstract: 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.
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