Computational Analysis on the Hydrodynamics of a Semisubmersible Naval Ship

Semisubmersible naval ships are versatile military crafts that combine the advantageous features of high-speed planing crafts and submarines. At-surface, these ships are designed to provide sufficient speed and maneuverability. Additionally, they can perform shallow dives, offering low visual and acoustic detectability. Therefore, the hydrodynamic design of a semisubmersible naval ship should address at-surface and submerged conditions. In this study, Numerical analyses were performed using a semisubmersible hull form to analyze its hydrodynamic features, including resistance, powering, and maneuvering. The simulations were conducted with Star CCM+ version 2302, a commercial package program that solves URANS equations using the SST k − ω turbulence model. The flow analysis was divided into two parts: at-surface simulations and shallowly submerged simulations. At-surface simulations cover the resistance, powering, trim, and sinkage at transition and planing regimes, with corresponding Froude numbers ranging from 0.42 to 1.69. Shallowly submerged simulations were performed at seven different submergence depths, ranging from D/L_OA = 0.063 5 to D/L_OA = 0.635, and at two different speeds with Froude numbers of 0.21 and 0.33. The behaviors of the hydrodynamic forces and pitching moment for different operation depths were comprehensively analyzed. The results of the numerical analyses provide valuable insights into the hydrodynamic performance of semisubmersible naval ships, highlighting the critical factors influencing their resistance, powering, and maneuvering capabilities in both at-surface and submerged conditions.