Modeling and Analysis of Underwater Vehicles Wake-Induced Electromagnetic Fields and Internal Wave Characteristics in a Stratified Ocean

To counter the threat of underwater vehicle stealth and meet the demand for non-acoustic detection, this study investigates the influence mechanism of underwater vehicle wakes in density-stratified ocean environments. Most existing studies are based on the uniform fluid assumption, neglecting the effects of internal waves induced by stratification. This paper establishes a novel mathematical model for the velocity field of an underwater vehicle wake in a stratified fluid, decomposing the wake into a linear superposition of surface wave and internal wave components. Based on electromagnetic induction theory, the expression for the induced electromagnetic field is derived. Through numerical simulations, the spatial distribution, attenuation patterns, and component contributions of the induced magnetic field are analyzed for underwater vehicles at depths ranging from 10 m to 50 m. The results indicate that in a stratified environment, the surface wave-induced magnetic field has a high peak value (0.15 nT in the near-field) but decays rapidly with distance. In contrast, the internal wave-induced magnetic field has a lower peak value (0.006 nT in the near-field) but is more stable and decays slowly, becoming dominant in the far-field. Furthermore, as the submergence depth increases, the contribution of the internal wave component grows significantly (reaching 84.9% in the near-field at a depth of 50 m). This study reveals, from both theoretical and simulation perspectives, that internal waves are the key physical mechanism for far-field detection, providing a new theoretical basis for developing non-acoustic detection technologies for underwater vehicles.