Numerical investigation on steady turning motion of a generic submarine near the free surface

This study investigated the steady turning motion of a generic submarine near the free surface using computational fluid dynamics (CFD) methods. The Joubert BB2 submarine and Marine 7371R propeller models were employed as the subjects of this research. The analysis utilized the Reynolds-averaged Navier-Stokes (RANS) equations with the SST k-ω turbulence model to capture turbulent flows, and the volume of fluid (VOF) method to capture the free surface dynamics. A mesh convergence study was conducted with three different mesh resolutions to ensure the accuracy of the simulations. An overset mesh method was used to control the submarine and its four control surfaces , while a sliding mesh approach simulated the propeller rotation. The self-propulsion point of the submarine was determined at a fixed speed using a PI controller . Subsequently, rudder maneuvers were executed to replicate a steady 20-degree turning motion. The study examined the effects of submergence depth and speed on the flow field. Results indicated an approximate 15% variation in turning parameters between the maximum and minimum submergence depths at the same speed, with force and torque differences around 30%. Additionally, the study explored the impact of the free surface on hydrodynamic forces , pressure distribution, free surface wave patterns, and vortex structures during turning maneuvers. • Proposed a simulation method to achieve steady turning motion of a generic submarine with X-rudders near the free surface. • Examined the effect of submergence depth and speed when the submarine conducted turning motions. • Evaluated the free surface waves and flow field characteristics during submarine turning motions.