Researchers have achieved notable advancements over the years in exploring ship damage and stability resulting from underwater explosions (UNDEX). However, numerous challenges and open questions remain in this field. In this study, the research progress of UNDEX load is first reviewed, which covers the explosion load during the shock wave and bubble pulsation stages. Subsequently, the research progress of ship damage caused by UNDEX is reviewed from two aspects: contact explosion and noncontact explosion. Finally, the research progress of ship navigation stability caused by UNDEX is reviewed from three aspects: natural factors, ship’s internal factors, and explosion factors. Analysis reveals that most existing research has focused on the damage to displacement ships caused by UNDEX. Meanwhile, less attention has been paid to the damage and stability of non-displacement ships caused by UNDEX, which are worthy of discussion.

This study investigates the hydrodynamic process of a cylinder ejected from the water’s surface through high-speed camera experiments. Using digital image processing methods, the images obtained through experiments are processed and analyzed. Although the dynamics of rising buoyant cylinders have been thoroughly investigated, the pop-up height of the cylinders has not been extensively explored. Statistical analysis of the kinematic and dynamic data of cylinders is conducted. Research has shown that after the cylinder rises, it pops out of the water’s surface. Within the experimental range, the pop-up height of the cylinder is related to the release depth. Furthermore, the pop-up height and release depth of the cylinder vary linearly under vertical release conditions. Under horizontal release conditions, the relationship between pop-up height and release depth shows irregular changes mainly because of the unstable shedding of the wake vortex.

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.

This study experimentally investigates the hydrodynamic characteristics, geometric configurations, fluttering motions of the codend, and the instantaneous flow fields inside and around the codend, with and without a liner, under varying catch sizes and inflow velocities. A proper orthogonal decomposition method is employed to extract phase-averaged mean properties of unsteady turbulent flows from flow measurement data obtained using an electromagnetic current velocity meter inside and around the codend. The results reveal that as catch size increases, the drag force, codend motion, Reynolds number, and codend volume increase while the drag coefficient decreases. Owing to the codend shape and pronounced motion, a complex fluid-structure interaction occurs, demonstrating a strong correlation between drag force and codend volume. The oscillation amplitudes of the hydrodynamic forces and codend motions increase with increasing catch size, and their oscillations mainly involve low-frequency activity. A significant reduction in the flow field occurs inside and around the unlined codend without a catch. The flow field is 5.81%, 14.39%, and 27.01% lower than the unlined codend with a catch, the codend with a liner but without a catch, and the codend with both a liner and a catch, respectively. Fourier analysis reveals that the codend motions and hydrodynamic forces are mainly characterized by low-frequency activity and are synchronized with the unsteady turbulent flow street. Furthermore, the proper orthogonal decomposition results reveal the development of unsteady turbulent flow inside and around the codend, driven by flow passage blockage caused by the presence of the liner, intense codend motions, and the catch. Understanding the hydrodynamic characteristics and flow instabilities inside and around the codend, particularly those associated with its fluttering motions, is crucial for optimizing trawl design and improving trawl selectivity.

As intelligent sensors for marine applications rapidly advance, there is a growing emphasis on developing efficient, low-cost, and sustainable power sources to enhance their performance. With the continuous development of triboelectric nanogenerators (TENGs), known for their simple structure and versatile operational modes, these devices exhibit promising technological potential and have garnered extensive attention from a broad spectrum of researchers. The single-electrode mode of TENGs presents an effective means to harness eco-friendly energy sourced from flowing water. In this study, the factors affecting the output performance were investigated using different structures of single-electrode solidliquid TENGs placed in a circulating water tank. In addition, the solid–liquid contact process was numerically simulated using the COMSOL Multiphysics software, and significant potential energy changes were obtained for the solid–liquid contact and liquid flow processes. Finally, the energy generated is collected and converted to power several light-emitting diodes, demonstrating that solid–liquid TENGs can generate effective electrical power in a flowing water environment. Through several experimental investigations, we finally determined that the flow rate of the liquid, the thickness of the friction electrode material, and the contact area have the most significant effect on the output efficiency of TENGs in the form of flowing water, which provides a guide for improving their performance in the future.