Spray Generation by a Plunging Breaker
Spray Generation by a Plunging Breaker
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DOI：
10.1029/2019gl082831
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发表时间：
2019-07-28
影响因子：
5.2
通讯作者：
Duncan, J. H.
中科院分区：
文献类型：
--
作者：
Erinin, M. A.;Wang, S. D.;Duncan, J. H.
本文介绍了一种由冲击波产生液滴的实验研究。在这项工作中，同时测量的波峰轮廓的演变和液滴范围内的半径下降到50 μ m的机械产生的暴跌断路器在许多重复的打破淡水事件。我们发现三个不同的时间区的液滴生产，第一，当射流冲击的波峰上游的自由表面，第二，当大气泡陷入的暴跌射流冲击到达自由表面和爆裂，第三，当较小的气泡爆裂后，在破碎过程中到达自由表面。这些子过程分别占每个破碎事件产生的平均653个液滴的22%、44%和34%。的概率分布的范围内的大，小液滴半径是很好地表示幂律函数相交的半径为418 μ m。简单的语言摘要海喷雾是众所周知的，大大提高了海洋和大气之间的质量，动量和能量的转移。以前的调查报告的时间平均液滴尺寸分布和通量在固定高度的风浪系统在海上和实验室规模的实验测量。人们普遍认为，液滴主要是由三个破碎子过程产生的：风切变（主要是在波峰），飞溅，破碎机夹带的气泡上升到自由表面的爆裂。然而，很少有实验数据，定量链接本地液滴生成特性，这些子过程。在这里，我们提出的结果，同时空间和时间分辨测量的波峰轮廓的演变和类似的解决测量的液滴范围内的半径下降到50 μ m的机械产生的暴跌断路器在许多重复的断裂事件。我们发现三个不同的时间区的液滴生产，第一，当射流冲击的自由表面，第二，当大的气泡捕获的暴跌射流冲击到达表面和爆裂，第三，当较小的气泡到达表面后，在破碎过程中。研究结果可用于逐步完善液滴运动和蒸发模型。
An experimental investigation of droplet generation by a plunging breaking wave is presented. In this work, simultaneous measurements of the wave crest profile evolution and of droplets ranging in radius down to 50 mu m for a mechanically generated plunging breaker during many repeated breaking events in freshwater are performed. We find three distinct time zones of droplet production, first when the jet impacts the free surface upstream of the wave crest, second when the large air bubbles entrapped by the plunging jet impact reach the free surface and burst, and third when smaller bubbles burst upon reaching the free surface later in the breaking process. These subprocesses account for 22%, 44%, and 34%, respectively, of the average of 653 droplets produced per breaking event. The probability distributions of the ranges of large and small droplet radii are well represented by power law functions that intersect at a radius of 418 mu m.Plain Language Summary Sea spray is known to dramatically enhance the transfer of mass, momentum, and energy between the ocean and the atmosphere. Previous investigations have reported measurements of temporally averaged droplet size distributions and fluxes at fixed heights in wind-wave systems at sea and in laboratory-scale experiments. It is commonly accepted that droplets are primarily produced by three breaking subprocesses: wind shear (primarily at the wave crest), splashing, and the popping of breaker-entrained air bubbles that rise to the free surface. However, there are little experimental data that quantitatively link local droplet generation characteristics to these subprocesses. Here we present the results of simultaneous spatially and temporally resolved measurements of the crest profile evolution and similarly resolved measurements of droplets ranging in radius down to 50 mu m for a mechanically generated plunging breaker during many repeated breaking events. We find three distinct time zones of droplet production, first when the jet impacts the free surface, second when the large air bubbles entrapped by the plunging jet impact reach the surface and burst, and third when smaller bubbles reach the surface later in the breaking process. The results of this research can be used in steps to improve models of droplet motion and evaporation.