| A ship carrying liquid carge with partially filled fluids in waves may experience violent sloshing. The ship motions excite slsohoing, which in return affects the ship motions. Therefore, it is very important for investigating the coupled effects between external wave and internal liquid sloshing flow under the wave action in engineering. In this paper, the coupled model is established for considering the motion response of ship in waves coupled with sloshing-induced internal sloshing and their effects on sloshing-induced impat loads. The linear ship motion is solved using an impulse-response-function (IRF) method, while the viscous sloshing flow is in simulated based on Navier-Stokes equation.For the external wave-structure action problem, the boundary element method (BEM) has been widely applied in the field of wave interaction with offshore structures, but it is still not easy to use in resolving large-scale problems because of computing costs and computer storage being increased by O(N2) for the traditional BEM. In this paper a Precorrected-FFT HOBEM is proposed for reducing the computational time and computer memory by O(N). Numerical results from the problems of wave interaction with single-and multi-bodies show that the present method evidently has more advantages in saving memory and computing time, especially for large-scale problems, than the traditional HOBEM. In addition, the optimal variable of pFFT mesh is recommended to minimize time cost. This work will be used in obtaining the external wave loads.And then, the viscous two-phase flow model with VOF interface capture technique based OpenFOAM package is established for solving the internal liquid sloshing problem. The numerical model is validated against available theoretical, numerical and experimental results in the published numerical results, especially the accuracy of flow fields solution, free surface capture, and local pressure impact by present method. Furthermore, numerical simulations are conducted to investigate the liquid sloshing problem in partially filled baffled tank. Special attention is paid to the nonlinear free surface evolution, mechanical energy dissipation and large amplitude sloshing motion in the liquid sloshing problem, especially around the resonant condition. It can be taken as the preparative and reference for the coupled analysis.Based on the above work, a coupled model has been adopted in my research which use Precorrected-FFT HOBEM and OpenFOAM package to consider both external wave-body interactions and internal viscous sloshing effects. The present model can be demonstrated that it is work well by the validation of rectangular tank surge motion coupling problem, rectangular tank roll motion coupling problem, and3D-LNG ship motion coupling problem. Moreover, the numerical simulation for the above three cases are carried out for analyzing the coupling effects of internal liquid sloshing coupled effects. For two rectangular tank coupled problem, the tank motion amplitude and internal sloshing forces in various internal liquid depth with different incident wave frequencies are investigated. The coupled hydrodynamic behavior and its reason are considered. For the coupled effects between3D-LNG ship motion and liquid sloshing under wave action problem, the influence of internal liquid depth, incident wave frequency and direction to ship global response is investigated. Furthermore, special attention is paid to the effects of incident wave amplitude. The global ship motions and local inside impact pressure on containers are investigated; the violent free surface sloshing motion such as breaking, overturning and splashing are examined, especially when the incident wave frequency is close to the natural frequencies of ship rolling motion or internal liquid sloshing. Finally, the inside impact pressure results by coupled analysis and uncoupled analysis are compared for the application of engineering. |
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