Bubble-sphere interaction beneath a free surface
Bubble-sphere interaction beneath a free surface
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自由表面下的气泡-球体相互作用
DOI：
10.1016/j.oceaneng.2018.09.032
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发表时间：
2018-12-01
影响因子：
5
通讯作者：
Wang, Shiping
中科院分区：
文献类型：
--
作者：
Li, Shuai;Khoo, Boo Cheong;Wang, Shiping
在实验和数值上研究了自由表面下方的气泡 - 球相互作用，这与水下爆炸和空化有关。我们使用电气排放技术来产生一个振荡的气泡，该气泡设置在可移动球体上方和自由表面下方。瞬态流体结构相互作用（FSI）通过高速成像记录。我们确定了三种独特的气泡喷气冲击模式，即（i）射流对球体顶部的撞击，它们之间的水层； （ii）气泡首先部分包裹球体，然后射流在没有水层的球面上撞击球面； （iii）射流会影响环形环，将气泡分成环形气泡和新的单一相互连接的气泡。这种瞬态FSI事件是通过边界积分方法建模的，并且上述气泡分裂由改进的涡流环模型建模。通过数值模拟，发现实验中的气泡，自由表面和球体动力学非常好。气泡动态行为与三个无量纲参数有关，并提供了对这些参数的系统研究。最后，讨论了球体表面上两种类型的空化现象，并分析了详细的物理机制。
The bubble-sphere interaction beneath a free surface is investigated experimentally and numerically, which is associated with underwater explosion and cavitation. We use the electric discharge technique to generate an oscillating bubble that is set above a movable sphere and below a free surface. The transient fluid-structure interaction (FSI) is recorded by high-speed imaging. We identify three distinctive bubble jet impact patterns, i.e., (i) jet impacts on the sphere top with water layer between them; (ii) the bubble partly envelops the sphere at first and then the jet impacts on the sphere top without water layer; (iii) the jet impacts on an annular ring, splitting the bubble into a toroidal bubble and a new singly-connected bubble. Such transient FSI events are modeled by the boundary integral method and the foregoing bubble splitting is modeled by an improved vortex ring model. The bubble, free surface, and sphere dynamics in experiments are found to be captured extremely well by numerical simulations. The bubble dynamic behaviors are associated with three dimensionless parameters and a systematic study of these parameters are provided. Lastly, the two types of cavitation phenomena on sphere surface are discussed and the detailed physical mechanisms are analyzed.