In order to study the mechanism of ice formation after water droplets produced by splashing waves attach to ship superstructure in cold ocean regions, a numerical framework that considers the effect of supercooling degree on the meso-scale water droplet freezing is developed to explore the freezing mechanism of water droplets after impacting. This model can track the solid–liquid and air–liquid interface together using a coupled volume-of-fluid and level set multiphase method and Enthalpy-Porosity phase change method. The model introduces a mixed fraction to describe the problem of three-phase unification. The simulation results of the center freezing height and droplet spreading factor in this paper are consistent with the experimental results in related literature, which verifies the accuracy of the framework. The study includes a detailed description of the dynamic and thermodynamics mechanism of the water droplet. The influence factors of droplet impacting and freezing process are analyzed. The analysis results show that the surface wettability, supercooling degree, and impact velocity have a great influence on the freezing behavior of droplets. This model can deepen the understanding of icing mechanism on ship superstructure surface, provide an indication for engineers to develop an accurate prediction method of ice accretion on ship superstructure surface.

The dynamics and thermodynamics of a supercooled water droplet impacting on a horizontal cold surface are investigated numerically. A two-dimensional axisymmetric model that considers both the non-equilibrium solidification caused by the supercooling and the dynamic contact angle (DCA) caused by the hysteresis phenomenon is developed to simulate the impacting, spreading, retraction, and freezing processes by combining the coupled volume-of-fluid and level set air–liquid interface capturing method and the Enthalpy-Porosity phase transition method. The common Kistler DCA model is applied to iteratively calculate the real time contact angle of three-phase contact point using the contact line velocity. The DCA model makes the simulation results of the spreading factor more accurate compared with the experimental data than the static contact angle model does. The non-dimensional maximum spreading factors of the room temperature and supercooled water droplet are almost the same in the low Weber number region, but quite different in the high one. The stable spreading factor is independent of the Weber number but increases with the decrease in the contact angle and the increase in the supercooling degree. This study can deepen the understanding of the impacting-freezing mechanism of a supercooled water droplet.

The vertical ice breaking of marine structures in ice-covered areas involves the deformation and failure of an ice sheet. Different from the existing conventional scenarios where the ice sheet is used as a transportation and support medium, the damage to the ice sheet will be more severe when a structure penetrates the ice sheet from below, due to the lack of elastic support from the fluid above the ice sheet. In order to investigate the failure mode of the ice sheet and the ice load characteristics during vertical penetration, a mesh-free bond-based peridynamic method is used in this paper to simulate the mechanical behaviors of the ice sheet. The cracks simulated in this study exhibit a higher level of similarity to experimental results, which improves the accuracy of the ice load. The numerical model established shows satisfactory applicability for the analysis of penetration failure of an ice sheet. In addition, the influence of ice thickness, impact velocity, and cylinder diameter on the failure characteristics of the ice sheet and breakthrough load are analyzed. The results of a parametric study indicate that the relationship between ice thickness and breakthrough load, as well as the relationship between load area and breakthrough pressure, can both be fitted using quadratic functions.

In this paper, a numerical model coupling the smoothed particle hydrodynamics (SPH) with peridynamics (PD) is developed to solve the problem of the hydroelastic water entry. By combining the geometric nonlinear peridynamics with the weakly compressible SPH, the proposed model can efficiently simulate the nonlinear deformation of the structure and the deformation of a fluid free surface. The transmission of information between the fluid and solid phases is implemented by a dummy particle boundary treatment method. By simulating benchmark tests, the ability of the proposed model to solve nonlinear fluid–structure coupling problems is verified. In order to improve the computational efficiency, the graphics processing unit parallel acceleration scheme is applied to the SPH-PD model. Compared with the serial scheme, the speedup effect of the parallel scheme in large-scale computation is verified. As an application of the numerical model, the water entry of the flexible panel at a constant entry velocity is studied. The mechanism of hydroelastic effect is explained by analyzing the variations in the fluid pressure field, slamming force, and panel deformation during water entry. In addition, the influences of plate rigidity, impact velocity, and deadrise angle on the hydroelastic effect are investigated.

This work focuses on investigating the correlation between the evolution of liquid bridges and moisture migration in solid bulk cargo liquefaction. We experimentally investigate the stability of liquid bridges in static and dynamic particles. The liquid-holding capacity of static particles is determined, and the formation and fracturing of liquid bridges are related to the particle distribution and particle radius. The spacing of the bottom particles determines the maximum liquid-holding capacity, while the space between the upper particles and the bottom particles determines the fracture position. The particles with larger radii have an increased liquid-holding capacity and a low volumetric moisture content, which confirms that cargo that consists entirely of large particles would be apt to have seepage and would not liquefy. Moisture migration for pendular and funicular liquid bridges during stretching and squeezing is captured. We indicate that the fusion behavior of liquid bridges is an important inducement for moisture migration, and it dramatically decreases the liquid-holding capacity. The findings suggest that cargo with low water content would still cause liquefaction, and that the water content should be reduced further for the safe transport of solid bulk cargo.