Abstract To investigate the complex cavity evolution, hydrodynamic action and motion response of a stone impacting on the water, a calculation model is established with six degrees of freedom. The Large Eddy Simulation (LES) model is used to solve the turbulence based on Computational Fluid Mechanics (CFD). The accuracy of the numerical model is verified by comparing the numerical results with experimental results. The stone is released above the free surface with different initial spinning velocities under a certain attack angle. The cavity dynamics, including the dome, open cavity and splash, are investigated during the impact process. Asymmetric impact cavity and the rotation around the y-axis are discovered. And the factors caused the rotation are analyzed. In particularly, there is a special cavity flow phenomenon found by the simulation that obvious tortuosity appears between first cavity and second cavity for a certain spinning velocity. Moreover, the hydrodynamic action, trajectory and reduce rate of velocity are studied for different spinning velocities. Compared to the non-spinning stone, the pressure distribution for the stone with spinning velocity is no longer regular and symmetrical. The maximum value of the pressure at the initial moment of the impact increases with increasing spinning velocity. The results demonstrate that the deviation in z-axis also increases with increasing spinning velocity. Furthermore, the trajectory of the stone with higher spinning velocity shows a more apparent bend in the o-xy plane. In the primary stage of impact, the spinning velocity of the stone decreases at a faster rate for the stone has a higher initial spinning velocity. Then, a transient increase of the reduce rate appears for the stone with violent tumble.

中文翻译：

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不同旋转速度石材空腔动力学三维数值模拟

摘要 为研究石块撞击水中复杂的空腔演化、水动力作用和运动响应，建立了六自由度计算模型。大涡模拟 (LES) 模型用于解决基于计算流体力学 (CFD) 的湍流。通过将数值结果与实验结果进行对比，验证了数值模型的准确性。石头在一定的攻角下以不同的初始旋转速度释放到自由表面上方。在冲击过程中研究了空腔动力学，包括圆顶、开放空腔和飞溅。发现不对称冲击腔和绕y轴旋转。并对引起旋转的因素进行了分析。特别是，模拟发现了一种特殊的腔体流动现象，在一定的旋转速度下，第一腔体和第二腔体之间出现明显的曲折。此外，研究了不同旋转速度下的流体动力作用、轨迹和速度降低率。与不旋转的石头相比，旋转速度的石头的压力分布不再规则和对称。冲击初始时刻的压力最大值随着旋转速度的增加而增加。结果表明，z 轴的偏差也随着旋转速度的增加而增加。此外，具有较高旋转速度的石头的轨迹在 o-xy 平面中显示出更明显的弯曲。在影响的初级阶段，石头的旋转速度下降得更快，因为石头具有更高的初始旋转速度。然后，剧烈翻滚的石头的减少率出现了短暂的增加。