Time-domain Simulation Of Liquid Sloshing In A Container Subjected To Complex Motions

Liquid sloshing is a kind of universal physical phenomenon. When the frequency of external excitation is close to the natural frequency of a container, liquid sloshing will tend to intense motion and resonance phenomenon may occur. In addition, the intense motion of liquid in a container induced by large movement will produce great pressure which may damage the structure. Therefore, the research about the characteristics of liquid sloshing is very meaningful.Based on the potential flow theory of ideal fluid, a fully nonlinear time-domain numerical model for liquid sloshing in a container is developed by a higher-order boundary element method. The present numerical model satisfies the basic governing equation of Laplace equation and the fully nonlinear kinematic and dynamic boundary conditions are satisfied on the free surface. In the computational process, the semi-mixed Eulerian-Lagrangian scheme is adopted to track the transient free surface. Meanwhile, the fourth-order Runga-Kutta method is used to refresh wave profile and velocity potential at the next time step and the grid division is also needed at every time step. In order to reduce computation and improve speed, image Green function is applied to the whole liquid domain to eliminate the integration at four laterals and bottom in3D problem and the integration at bottom in2D problem.Liquid sloshing in four conditions are mainly considered in the present work, including free sloshing with initial surface in a container, complex motion of surge and heave, complex motion of surge, heave and pitch, complex motion of surge, sway and heave. Through comparison with the published numerical results and experimental data at two aspects of wave surface and hydrodynamic pressure, the present numerical model is validated to be accurate to simulate liquid sloshing in a container subjected to various complex motions. Then, the effect of various factors on liquid sloshing is researched in detailed, including the movement frequency, the movement intensity, the rotational center and so on. It is found that odd order natural frequency is excited easily compared with even order natural frequency in case of free sloshing. External excitation frequency equal to odd order natural frequency can induce resonance, but even order natural frequency won’t. Meanwhile, movement intensity and rotational center effect liquid sloshing directly. Besides, liquid sloshing in container with horizontal baffle or vertical baffle of different number and scale is also considered and the effect of baffle parameter is researched to provide certain reference for engineering design.