ALE动网格法在流固耦合数值模拟中的应用

Application of dynamic grid of ALE to Numerical Simulation of Coupling Motion of Fluid and Solid

为了解决流固耦合问题中的物体大幅度运动带来的困难,采用ALE(Arbitrary Lagrange-Euler)动网格方法跟踪自由表面上浮体的运动。计算表明:浮体在无粘流体中的垂荡与弹簧-物体的振动模型理论解符合得较好;浮体在粘性流体中的自由横摇为阻尼运动,其横摇角度随时间的增加而减小,且在不同初始角度下运动系统的固有周期相当。在有外力力矩激励时,外力力矩的周期与系统的固有周期相当时浮体横摇运动趋于共振状态,运动幅度最大。计算结果验证了计算程序的可靠性与精度。本文方法为ALE方法应用于流体-多浮体耦合运动分析奠定了基础。

Most of theories for rolling of ships and pontoons are under the assumption of small motion am-plitudes. To solve the difficulties of large amplitude motion of floating body, the ALE (Arbitrary Lagrange-Euler) method is used to track the motion of at free surface. The results show that the heave motion in inviscid flow is matched well with the model of spring-object vibration. But in viscous flow, the motion of the floating body is featured as damping vibration, whose rolling angle decreases with the time. And the difference among the motion periods at different cases of initial list angles gets very small. The list vibration of floating body agrees well with the analytical solution at the case of small list angle. The motion of the floating body trends to sympathetic vibrate and the motion amplitude trends to the maximal value when the period of external moment approaches to the natural period of the system.