The effects of surfactants on spilling breaking waves
The effects of surfactants on spilling breaking waves
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DOI：
10.1038/nature01357
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发表时间：
2003-01-30
期刊：
影响因子：
64.8
通讯作者：
Duncan, JH
中科院分区：
文献类型：
--
作者：
Liu, XN;Duncan, JH
破碎波显著增加了海气动量、能量和质量的转移率(1-4)。在微风到中风的条件下，经常观察到波长较短的溢流断路器。理论和实验室实验表明，当这些波在干净的水中接近破裂时，由表面张力主导的波纹在波峰形成(5-14)。在实验室条件下和理论上，向湍流的转变是由波纹下的流动分离触发的，通常不会导致自由表面(15)的倾覆。然而，自然界中的水面通常被表面活性剂薄膜污染，这些薄膜会改变表面张力并产生表面弹性和粘度(16，17)。在这里，我们介绍了实验室实验的结果，在这些实验中，在一定的表面活性剂浓度范围内，在水中机械地产生了溢出破碎波。我们发现，由于表面活性剂的存在，破碎过程发生了显著的变化。在表面活性剂浓度最高时，一股小的下沉射流从波峰下方的波前射出，并在与波前撞击时卷起一袋空气。在这一过程中产生的气泡和湍流可能会增加海气之间的转移。
Breaking waves markedly increase the rates of air-sea transfer of momentum, energy and mass(1-4). In light to moderate wind conditions, spilling breakers with short wavelengths are observed frequently. Theory and laboratory experiments have shown that, as these waves approach breaking in clean water, a ripple pattern that is dominated by surface tension forms at the crest(5-14). Under laboratory conditions and in theory, the transition to turbulent flow is triggered by flow separation under the ripples, typically without leading to overturning of the free surface(15). Water surfaces in nature, however, are typically contaminated by surfactant films that alter the surface tension and produce surface elasticity and viscosity(16,17). Here we present the results of laboratory experiments in which spilling breaking waves were generated mechanically in water with a range of surfactant concentrations. We find significant changes in the breaking process owing to surfactants. At the highest concentration of surfactants, a small plunging jet issues from the front face of the wave at a point below the wave crest and entraps a pocket of air on impact with the front face of the wave. The bubbles and turbulence created during this process are likely to increase air-sea transfer.