Identifying Wave and Vortex Signatures of Subsurface Wakes amid Background Internal Waves

The passage of towed bodies through stratified fluids, such as the ocean, generates near-field quasi-two-dimensional vortices and far-field internal waves. Vortex signatures emerge from wake instabilities, meandering and vortex shedding, which lead to the formation of a quasi-two-dimensional vortex sheet with coherent spacing. Internal wave signatures, which arise from the collapse of the density anomaly created as the object passes through the fluid, radiate outward in a coherent, modal wave pattern These signatures are leveraged to develop physics-based tools for identifying the presence of the wake amid the noise of background internal waves. The tools are applied to numerical simulations with varying wake parameters and levels of background internal wave energy. Vortex signatures are detected through spectral analyses of one-dimensional transects in the direction of the wake axis. Wave signatures are detected by projecting full-field data onto known two-dimensional modal structures. These minimal spatial sampling approaches enable efficient signal detection without requiring full three-dimensional data. Results demonstrate how wake parameters and background internal waves influence the detectability and persistence of a wake within a realistic ocean environment.