The bow-flared section may be simplified in the prediction of slamming loads and whipping responses of ships. However, the difference of hydrodynamic characteristics between the water entry of the simplified sections and that of the original section has not been well documented. In this study, the water entry of several different bow-flared sections was numerically investigated using the computational fluid dynamics method based on Reynolds-averaged Navier–Stokes equations. The motion of the grid around the section was realized using the overset mesh method. Reasonable grid size and time step were determined through convergence studies. The application of the numerical method in the water entry of bow-flared sections was validated by comparing the present predictions with previous numerical and experimental results. Through a comparative study on the water entry of one original section and three simplified sections, the influences of simplification of the bow-flared section on hydrodynamic characteristics, free surface evolution, pressure field, and impact force were investigated and are discussed here.

Water is very important as an extinguishing material. However, it is difficult to put out the fire for the long-range or complex environment because of vulnerable, dosage and low efficiency. In this paper, a kind of high-efficiency water-soluble fire extinguishing agent was developed. The results show that the effective firefighting distance was increased by more than 40% and firefighting time was reduced by more than 1/3 when the fire extinguishing agent was used.

Underwater robots demonstrate significant potential for hull biofouling removal. However, achieving uniform and damage-free cleaning remains a persistent challenge. The fixed arrangement of cleaning mechanisms, combined with the inherent non-uniformity of cavitation jet energy distribution, frequently results in inconsistent removal depths, leading to local over-cleaning or under-cleaning. To address this, this paper proposes an optimization framework to coordinate the robot’s motion with its cleaning mechanism. First, the flow field dynamics of the cavitation nozzle are elucidated using the Stress-Blended Eddy Simulation (SBES) turbulence model. Based on the Computational Fluid Dynamic (CFD) data, a Gaussian mapping model is constructed to quantify the relationship between jet erosion efficiency and robotic motion parameters. Furthermore, to resolve the multi-objective coverage parameter optimization problem, an improved hybrid metaheuristic algorithm—the Composite Cycloid Subtraction-Average-Based Optimizer (CCSABO)—is introduced to determine the optimal synchronization of forward and lateral velocities. Numerical simulations demonstrate the framework’s robustness across various fouling thickness scenarios and nozzle parameters. Notably, the CCSABO algorithm achieves a coverage rate of 99% and minimizes the uniformity index to 0.011, demonstrating superior consistency compared to traditional PSO and GWO methods. This improvement effectively mitigates the risk of hull damage while ensuring cleaning quality.

Using computational fluid dynamics (CFD) coupled with the volume of fluid (VOF) method, we developed an analytical framework to quantify free-surface suction around ship hulls. The DTMB 5415 benchmark hull was employed to investigate the mechanisms by which underwater tail fins influence surface wake dynamics. We systematically evaluated the effects of tail-fin span on hydrodynamic drag and free-surface suction across the investigated speed range. Within the Froude number range of 0.05–0.45, underwater tail fins reduced air entrainment by optimizing hull attitude and attenuating stern waves. Free-surface suction capacity exhibited a positive correlation with vessel speed and a negative correlation with tail-fin span length. At Fr = 0.45, the free-surface suction capacity of the bare hull was 13.78 times greater than that at Fr = 0.15. At this speed, the L₄ tail-fin configuration achieved a 13.292% reduction in free-surface suction. In contrast, the L₂ tail-fin configuration provided a suction reduction of only 9.98%. The optimal tail-fin span represents a trade-off between drag reduction and wake suppression, as longer spans do not necessarily yield superior performance. Under cruise conditions (Fr = 0.25–0.35), the L₂ tail-fin configuration exhibited optimal performance, achieving a 5.292% reduction in drag and a 13.492% reduction in free-surface suction. Across the tested Froude number range of 0.05–0.45, underwater tail fins simultaneously improved hydrodynamic performance and reduced free-surface suction, thereby effectively suppressing bubble wake formation.

As an important carrier for integrating cross-university educational resources and promoting the collaborative development of higher education, multi-university joint teaching teams play an irreplaceable role in improving teaching quality, promoting teachers’ professional development, and cultivating compound talents. Based on practical data and cases from multiple domestic universities, this paper systematically analyzes the current situation of the construction of multi-university joint teaching teams, reveals core issues such as unbalanced team structure, poor collaboration mechanisms, and insufficient resource guarantees, and proposes targeted paths from aspects of optimizing team structure, improving collaboration mechanisms, and strengthening institutional guarantees. The research shows that by constructing an integrated model of “inter-university collaboration - resource sharing - dynamic evaluation”, the operational efficiency of joint teaching teams can be effectively improved, providing strong support for the connotative development of higher education.