Numerical analysis of the far wake flow behind a submarine with full appendages

Wake flow behind underwater vehicles such as submarines was widely researched with its impacts on propulsion or antisubmarine technology. Extensive research was performed on the near wake for its hydrodynamics of propulsion, but the far wake flow was given less attention owing to its huge challenges and expensive costs. In this study, a long-range wake evolution behind a full-size Suboff submarine with full appendages is numerically investigated by the Delayed Detached Eddy Simulation (DDES) method, which provides a reference for submarine shape design and wake detection. Evolution of vortex structures near the sail and tail is detailed, including the modes of horseshoe vortex, hairpin vortex and tip vortex. The diffusion of vortex along the wake at specific speed is also focused, by using a slice analysis of vorticity and velocity. When dimensionless velocity profiles in different slices of the wake are stacked up, the overlay shows a pretty coincident contour in velocity deficit behind the submarine. The equations for velocity deficit and wake range are fitted by the orthogonal distance regression principle for further application.