AN ESTIMATE OF THE KELVIN IMPULSE OF A TRANSIENT CAVITY
AN ESTIMATE OF THE KELVIN IMPULSE OF A TRANSIENT CAVITY
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DOI：
10.1017/s0022112094000273
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发表时间：
1994-02-25
影响因子：
3.7
通讯作者：
BLAKE, JR
中科院分区：
文献类型：
--
作者：
BEST, JP;BLAKE, JR
拉加利定理用于根据流体速度势的奇点（通过解析延拓在气泡内定义）来获得作用于气泡上的比耶克尼斯力的表达式。该表达式应用于边界附近的瞬态空腔塌陷，从而可以对空腔的开尔文脉冲进行分析估计。恢复了水平刚性边界附近塌陷的已知结果，并估计了浸没和部分浸没球体附近塌陷空腔的开尔文脉冲。开发了一种数值方法来处理更一般的身体形状，特别是旋转体。注意到塌陷阶段结束时的脉冲方向通常指示可能形成的液体射流的方向，因此预测了这些几何形状中的瞬态空腔的行为。在这些例子中引入了吸引力区域的概念。这是身体周围的一个区域，在该区域内，塌缩时的开尔文脉冲以及随后形成的射流预计将被导向身体。在该区域之外，情况正好相反。
The Lagally theorem is used to obtain an expression for the Bjerknes force acting on a bubble in terms of the singularities of the fluid velocity potential, defined within the bubble by analytic continuation. This expression is applied to transient cavity collapse in the neighbourhood of boundaries, allowing analytical estimates to be made of the Kelvin impulse of the cavity. The known result for collapse near a horizontal rigid boundary is recovered, and the Kelvin impulse of a cavity collapsing in the neighbourhood of a submerged and partially submerged sphere is estimated. A numerical method is developed to deal with more general body shapes and in particular, bodies of revolution. Noting that the direction of the impulse at the end of the collapse phase generally indicates the direction of the liquid jet that may form, the behaviour of transient cavities in these geometries is predicted. In these examples the concept of a zone of attraction is introduced. This is a region around the body, within which the Kelvin impulse at the time of collapse, and consequent jet formation, is expected to be directed towards the body. Outside this zone the converse is true.