水平变化波导中的简正波耦合与能量转移

针对海底地形水平变化对声场能量传播和声场干涉结构的影响,对简正波之间的耦合和能量转移进行了研究.建立了一种二维大步长格式的耦合简正波模型和三维楔形波导耦合简正波模型,以便快速有效地分析简正波之间的耦合和能量转移.基于耦合简正波模型,阐述了前向声场能量在水平变化波导中传播时的转移过程.并根据射线简正波理论,解释了海底地形变化对声场能量分布的影响机理.水平变化波导中声场的仿真计算表明,当本征值虚部发生剧烈变化时声场存在着较强的简正波耦合和能量转移,且海底地形变化将导致声场能量的水平传播方向偏转至海水深度增加的方向.在声场能量转移和传播方向变化中,声场的能量趋于保留在波导中而不向海底泄漏.同时,声场能量分布受到类似于压缩或稀疏的作用,从而形成椭圆状的干涉结构.

Mo de coupling and energy transfer in a range-dep endent waveguide

The mode coupling and energy transfer are studied by considering the influences of variation in topography on sound energy transmission and structures of interference in a range-dependent waveguide. A larger level-stepped coupled mode model and a three-dimensional coupled mode model for the wedge bottom are obtained such that the mode coupling and energy transfer may be analyzed efficiently and rapidly. According to the coupled mode models, the transfer of energy is expounded for the forward pressure field in the waveguide with varying topography. Meanwhile, the mechanism is explained by the ray-mode theory for variation of energy distribution caused by variation of topography. Numerical simulations show that the coupling between normal modes and the energy transfer may occur remarkably when the imaginary parts of eigenvalues take on a huge modification, and the propagation direction of sound field will be changed to the increasing direction of sea depth due to variation of topography. In the energy transfer and the modification of propagation direction, the energy of sound field tends to remain in the waveguide, rather than to leak to the seafloor. Meanwhile, the energy distribution will be affected by the compression or sparseness so that interference structures such as ellipse, will be produced.
Keywords： mode coupling energy transfer range-dependent waveguide