Hydrodynamic Performance of an Underwater Glider with Bottom Cabins for Different Operating Modes

Underwater gliders are widely used in ocean observation and environmental monitoring due to their high energy efficiency and long endurance. However, to perform complex underwater operations, they often need cabins on both sides of the bottom hull for installing manipulator arms, which alters the hull structure and flow characteristics. This study uses computational fluid dynamics (CFD) simulations to comparatively analyze the glider’s hydrodynamic performance under three representative operating modes: (1) closed-cabin; (2) single-side opening (single manipulator arm operation); (3) dual-side opening (dual manipulator arm cooperative operation). The numerical results show that opening the bottom cabins significantly changes the glider’s force distribution and stability. Single-side opening breaks flow field symmetry, leading to a significant increase in drag and a large rolling moment, which greatly reduces navigation stability. Although dual-side opening increases drag more, its symmetrical layout effectively offsets part of the induced moment, resulting in overall stability superior to the single-side opening mode. These findings provide theoretical guidance for optimizing the structural design and performance balance of underwater gliders equipped with manipulator arms.