Numerical Simulation of the Water Entry of a Structure in Free Fall Motion

To solve the problems concerning water entry of a structure, the RANS equations and volume of fluid （VOF） method are used. Combining the user-defined function （UDF） procedure with dynamic grids, the water impact on a structure in free fall is simulated, and the velocity, displacement and the pressure distribution on the structure are investigated. The results of the numerical simulation were compared with the experimental data, and solidly consistent results have been achieved, which validates the numerical model. Therefore, this method can be used to study the water impact problems of a structure.

Correlation analysis of three influencing factors and the dust production rate for a free-falling particle stream

The effects of three factors （i.e., drop height h, hopper outlet diameter do, and material temperature T] on the dust generation rate derived from a free falling particle stream were investigated via filll factorial experiments. The correlation between the three factors and dust generation rate was also analysed. Results show that Tand h affect the first fugitive dust rate largely, whereas the second fugitive dust rate is mainly dominated by h and do. Through analysing the first fugitive dust percentage data, it is found that h and T should be considered first for higher temperatures and lower flow rates, whereas h and do can be considered under contrasting conditions, and h should be controlled in the remaining two sets of conditions. Relationships between the influencing factors and total and first fugitive dust rates were developed via multiple regression to quantify the dust emission rates for different contact surfaces （rigid or water）.

Numerical investigation and its application on the falling motion of freefall lifeboat

In order to improve the simulation accuracy for free-fall lifeboat in ship life-saving training system,this paper analyzes and models the motion of boat’s launching from the skid.The whole launching is divided into four phases,namely:sliding down,rotation,free fall and water entry.According to the theory of momentum and strip theory,hydrodynamic forces of the boat at water entry are calculated under the effect of waves.The method of interpolation is used for calculating the half width and added mass of cross-sections at water entry.The model is used for numerical investigation about the boat launching from skid under different conditions and applied to ship life-saving simulation training system.The following conclusions are finally obtained:(1)When the initial inclination angle is 30◦,the horizontal distance between the point of water entry of the boat and the lower end of the slide is about 7.2 m.The horizontal distance will be smaller,when the initial inclination angle increases.There is no obvious law between forward distance and waves.(2)When the initial inclination angle is 45◦,the setback may occur after the boat entering the wave.When the initial angle is 60◦,the setback occurs after the boat entering the water.(3)When the center of gravity is 1.5 m in front of the midship of the boat,the boat will turn over.

Gravity-induced geometric spin Hall effect of freely falling quantum particle

We discuss a new gravitational effect that the wave packet of a free-fall quantum particle undergoes a spin-dependent transverse shift in Earth’s gravitational field.This effect is similar to the geometric spin Hall effect(GSHE)(Aiello 2009 et al Phys.Rev.Lett.103100401),and can be called gravity-induced GSHE.This effect suggests that the free-fall wave packets of opposite spin-polarized quantum particles can be split in the direction perpendicular to spin and gravity.

Simulation of water entry of an elastic wedge using the FDS scheme and HCIB method

The hydroelasticity of water entry of an elastic wedge is simulated using a code developed using the flux-difference splitting scheme for immiscible and incompressible fluids and the hybrid Cartesian/immersed boundary method. The free surface is regarded as a moving contact discontinuity and is captured without any additional treatment along the interface. Immersed boundary nodes are distributed inside a fluid domain based on the edges that cross an instantaneous body boundary. Dependent variables are reconstructed at each immersed boundary node with the help of an interpolation along a local normal line for providing a boundary condition for a discretized flow problem. A dynamic beam equation is used for modeling the elastic deformation of a wedge. The developed code is validated through comparisons with other experimental and computational results for a free-falling wedge. The effects of the elastic deformation of the wedge on the pressure fields and time histories of the impact force are investigated in relation to the stiffness and density of the structure. Grid independence test is carried out for the computed time history of the force acting on an elastic wedge.