Numerical analysis of water exit for a sphere with constant velocity using the lattice Boltzmann method |
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| Institution: | 1. School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, PR China;2. College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, PR China;1. Department of Ocean Engineering, Amirkabir University of Technology, Tehran 15914, Iran;2. Department of Aerospace Engineering, Sharif University of Technology, Tehran 11115-8639, Iran |
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| Abstract: | In this paper, the three-dimensional water exit of a sphere with different vertical velocities is investigated numerically using the lattice Boltzmann method (LBM). In this method, the liquid-gas two-phase flow is simplified as a single-phase free surface flow. To capture the free surface, a mass tracking algorithm is incorporated into the LBM. The gravity as a body force is introduced in the form of calculating the equilibrium distribution with an altered velocity, while the surface tension is neglected. Besides, the employed bounce-back boundary conditions are used for a moving sphere. What’s more, the Wall-Adapting Local Eddy (WALE) viscosity model is employed to capture the turbulent structures of the flow and stabilize the simulation. The accuracy of the numerical results is demonstrated through comparisons with the previous numerical and experimental results in the literature. The results show that the spike height is significantly influenced under the Froude number (Fr) below 4.12 and slightly affected under the Fr varying from 4.12 to 8.24. After the sphere exits water totally, the evolution of the free surface waterfall can be described as two phases and becomes more intense with the Froude number increasing. The non-uniform distribution of velocity results in the breaking of the free surface after the sphere completely exits the water. Moreover, the Reynolds number greatly affects the wake dynamics and hydrodynamics acting on the sphere when it moves beneath the water surface. |
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| Keywords: | Lattice Boltzmann method (LBM) Numerical simulation Water-exit of a sphere Deformation of free surface Wake dynamics and hydrodynamics |
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