Pressure Oscillations during Wave Impact on Vertical Walls
Pressure Oscillations during Wave Impact on Vertical Walls
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DOI：
10.1061/9780872629332.124
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
M. Topliss;M. Cooker;D. Peregrine
中科院分区：
文献类型：
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作者：
M. Topliss;M. Cooker;D. Peregrine
这一研究领域涉及垂直结构物上的波浪冲击压力。风暴期间可能会对海岸防御造成严重破坏，已经进行了大量的实验室实验，以了解物理过程。本文给出了在水波冲击测量中观察到的高频压力振荡的数学描述，特别是对垂直壁面的冲击。我们的最终目标是追踪压力波动的物理根源，这与理解流体可压缩性在破碎波冲击压力中的作用有关。一些作者提出，记录到的压力振荡是由充气气泡的振动引起的，例如Wegel&Maxwell(1970)的一些声波传播模型。此外，众所周知，水中小体积分数空气的可压缩性会极大地降低混合物中的声速。我们通过简化几何结构和求出自由振动的频率来研究可能的情况。我们忽略了主流水，因为它具有较长的时间尺度。我们最初的模型考虑了靠近壁面的可压缩充气水和更远的具有更高声速的可压缩非充气水。这与气囊被困在不可压缩水中靠墙的一个简单例子进行了比较。与三个实验结果的比较是令人鼓舞的。
This area of study concerns wave impact pressure on vertical structures. Severe damage can be inflicted on coastal defences during storms and numerous laboratory experiments have been undertaken to gain an understanding of the physical processes. This paper gives a mathematical description of high frequency pressure oscillations which are observed in measurements of water-wave impacts; particularly impact against a vertical wall. Our ultimate aim is to trace the physical origins of the pressure fluctuations which are related to the understanding of the role of fluid compressibility in breaking wave impact pressure. It has been suggested by some authors that the recorded pressure oscillations are due to the vibrations of air-filled gas bubbles, for example Weggel & Maxwell (1970) model some details of acoustic wave propagation. In addition, it is well known that the compressibility of a small volume fraction of air in water dramatically reduces the velocity of sound in the mixture. We investigate possible cases by simplifying the geometry and finding the frequency of free oscillations. We ignore the main flow of water since it has a longer time-scale. Our initial model considers compressible aerated water near the wall and compressible non-aerated water with a much higher sound speed further away. This is compared with a simple example of an air pocket trapped against a wall in incompressible water. Comparisons with three experimental results are encouraging.