Controlled impact of a disk on a water surface: cavity dynamics
Controlled impact of a disk on a water surface: cavity dynamics
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DOI：
10.1017/s0022112009006983
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发表时间：
2008-04
影响因子：
3.7
通讯作者：
R. Bergmann;D. Meer;S. Gekle;A. Bos;D. Lohse
中科院分区：
文献类型：
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作者：
R. Bergmann;D. Meer;S. Gekle;A. Bos;D. Lohse
本文研究了半径为0的圆盘在弗劳德数低于200的水面上受控撞击所产生的瞬态表面空腔。用高速成像技术记录了瞬态自由表面的动力学，并与边界积分模拟结果进行了比较，得到了很好的一致性。用高速粒子图像测速仪对腔体周围的流动进行了测量，结果与模拟得到的流场吻合较好。我们提出了一个基于无限圆柱体坍塌的腔体径向动力学的简单模型。该模型解释了观察到的腔体膨胀和收缩阶段之间径向动力学的不对称性。它再现了闭合深度和腔体总深度的尺度，这两个尺度都被发现大致为∝Fr1/2，具有弱弗劳德数相关的前因子。此外，该模型准确地捕捉了空腔最小半径的动态变化和过程中夹带空气体积Vbubble的尺度变化，即Vbubble/h03∝(1 + 0.26Fr1/2)Fr1/2。
In this paper we study the transient surface cavity which is created by the controlled impact of a disk of radius h0 on a water surface at Froude numbers below 200. The dynamics of the transient free surface is recorded by high-speed imaging and compared to boundary integral simulations giving excellent agreement. The flow surrounding the cavity is measured with high-speed particle image velocimetry and is found to also agree perfectly with the flow field obtained from the simulations. We present a simple model for the radial dynamics of the cavity based on the collapse of an infinite cylinder. This model accounts for the observed asymmetry of the radial dynamics between the expansion and the contraction phases of the cavity. It reproduces the scaling of the closure depth and total depth of the cavity which are both found to scale roughly as ∝ Fr1/2 with a weakly Froude-number-dependent prefactor. In addition, the model accurately captures the dynamics of the minimal radius of the cavity and the scaling of the volume Vbubble of air entrained by the process, namely, Vbubble/h03∝(1 + 0.26Fr1/2)Fr1/2.