Minimum size for the top jet drop from a bursting bubble
Minimum size for the top jet drop from a bursting bubble
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DOI：
10.1103/physrevfluids.3.074001
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发表时间：
2018-07-11
影响因子：
2.7
通讯作者：
Bird, James C.
中科院分区：
文献类型：
--
作者：
Brasz, C. Frederik;Bartlett, Casey T.;Bird, James C.
从破裂的气泡中喷出的喷射水滴无处不在，它将含气饮料中的芳香物质、受污染水源中的病原体以及海洋表面的海盐和有机物种输送到大气中。在所有这些过程中，最小的液滴值得注意，因为它们的缓慢沉降速度允许它们比大液滴持续更长时间和旅行更远，前提是它们逃离粘性亚层。然而，目前还不清楚这些喷气式液滴能变得多小的上限是什么。在这里，我们直接观察到微尺度喷滴的形成，并证明了最小的喷滴不是由最小的喷滴产生的气泡产生的，正如Duchemin等人数值预测的那样。作者声明：[Duchemin et al.流体14,3000(2002)]。通过高速成像和数值模拟相结合的方法，我们证明了最小喷滴尺寸是由粘性力和惯性毛细管力在喷流形成前后的相互作用决定的。在观察到自相似射流生长的基础上，将射流液滴尺寸分解为形状因子和射流生长时间，使液滴尺寸与气泡尺寸的非单调关系合理化。这些发现为从海洋中的喷气滴产生亚微米气溶胶提供了限制。
Jet drops ejected from bursting bubbles are ubiquitous, transporting aromatics from sparkling beverages, pathogens from contaminated water sources, and sea salts and organic species from the ocean surface to the atmosphere. In all of these processes, the smallest drops are noteworthy because their slow settling velocities allow them to persist longer and travel further than large drops, provided they escape the viscous sublayer. Yet it is unclear what sets the limit to how small these jet drops can become. Here we directly observe microscale jet drop formation and demonstrate that the smallest jet drops are not produced by the smallest jet drop-producing bubbles, as predicted numerically by Duchemin et al. [Duchemin et al., Phys. Fluids 14, 3000 (2002)]. Through a combination of high-speed imaging and numerical simulation, we show that the minimum jet drop size is set by an interplay of viscous and inertial-capillary forces both prior and subsequent to the jet formation. Based on the observation of self-similar jet growth, the jet drop size is decomposed into a shape factor and a jet growth time to rationalize the nonmonotonic relationship of drop size to bubble size. These findings provide constraints on submicron aerosol production from jet drops in the ocean.