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Objects entering water is a complex multiphase flow event that exhibits nonlinear and transient characteristics. This study examines the impact cavities, multiphase flow characteristics, and motion behaviors of a cylinder during vertical water entry, considering different flow and entry velocities. A three-dimensional model was carried out using OpenFOAM® framework, taking into account the effects of wind and linearly sheared flow through newly customized initial and boundary conditions. The overset mesh technique was applied to capture the water entry trajectories of the moving cylinder. Numerical results for the cavity evolution and cylinder motion behaviors were validated against published laboratory tests. The cavity closure patterns were classified into four categories based on the evolution characteristics, which were found to be more complex than those observed under calm water and uniform current conditions. Furthermore, the rapid closure of the splash dome results in a unique cavity flow phenomenon, which creates a suction air channel. The velocities of the flow and water entry have a noticeable impact on the closure modes and time of the cavity. This, accordingly, affects the motion characteristics of the cylinder, as well as the evolution of the velocity field, pressure field, and vortex structures. [ABSTRACT FROM AUTHOR]

The process of a damaged ship flooding is a complicated free surface flow problem. There is a complex coupling effect between the ship cabin and the flow inside and outside of the cabin. In this paper, a GPU (graphic processing unit)- δ + -SPH (smoothed particle hydrodynamics) numerical model for the cabin flooding in deep-water environments is developed based on GPU parallel acceleration technology and Nvidia's CUDA (compute unified device architecture). First, the computational accuracy and efficiency of this numerical model are verified by experiments results on the water flooding of a simple damaged cabin model. Furthermore, the flooding characteristics of a submarine cabin are analyzed, considering different numbers of damaged cabins, depths, and opening positions. Finally, the progressive flooding and the dynamic response characteristics of a full-scale submarine model are investigated. The results show that the process of progressive flooding in a submarine cabin is characterized by its rapidity and intensity. Different factors, for example, damaged cabin numbers, cabin depths, and opening positions, have great influences on the process of flooding and the motion of the submarine cabin. This study can offer valuable technical assistance in the post-damage remediation process. [ABSTRACT FROM AUTHOR]

For the special ship like catamaran, which has a unique structure with gap resonance, the traditional potential method tends to over-predict the motion at the resonance frequency due to the negligence of fluid viscosity. In this paper, a new method considering damping is put forward to inhibit over-predicted heave and pitch response. Viscous damping is introduced into free surface boundary conditions. Critical damping is added in the motion equations. Numerical simulations of a HEU catamaran and a DUT catamaran are performed. It is found both viscous damping and critical damping can weaken the over-predicted resonant responses. However, the method of adding critical damping is much more efficient at high speeds and the results conform better to the experimental results. [ABSTRACT FROM AUTHOR]

In this paper, the cytotoxicity of EGCG against PC-3 prostate cancer cells and its molecular mechanism in the presence and absence of Zn2+ in vitro were investigated. The results showed that both EGCG and Zn2+ suppressed clonegenecity of PC-3 cells, and the suppression effect was enhanced in the coexist system of EGCG and Zn2+. MMP-9 is thought to play a significant role in cancer cell migration and invasion. In the present paper, the results showed that EGCG suppressed the activity of MMP-9 in PC-3 cells in the presence of Zn2+, as a result, migration ability of the cells was significantly decreased.