The breakup of levitating water drops observed with a high speed camera
The breakup of levitating water drops observed with a high speed camera
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DOI：
10.5194/acp-11-10205-2011
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发表时间：
2011-01-01
影响因子：
6.3
通讯作者：
Connolly, P. J.
中科院分区：
文献类型：
--
作者：
Emersic, C.;Connolly, P. J.
使用高速摄像机观察了垂直风洞中碰撞引起的水滴破裂，以观察比之前实验观察到的更大的水滴尺寸（直径达 7 毫米）之间的相互作用。观察到三种不同的碰撞破碎类型，并分析每种类型的液滴尺寸分布，以便与通过两组已建立的破碎参数化对较大液滴的碎片分布的预测进行比较。观察结果表明，两种参数设置有一些相似之处，但可比较的破碎类型也存在一些显着差异，特别是对于 1 毫米或更小的碎片。建议并检查对参数设置的修改。还提供了目前观察到的最大的袋子破裂分布数据集。讨论了该研究与其他实验研究和建模参数化之间的差异，以及解释结果的相关含义。此外，使用破碎参数化计算求解随机聚结和破碎方程，并检查了一系列初始条件下不断变化的液滴尺寸分布。发现初始云液态水含量对所得分布影响最大，而初始滴数影响相对较小。当考虑气溶胶对云演化、雨滴形成和由此产生的雨滴尺寸分布的影响时，这可能会产生影响。计算表明，使用理想的初始云滴尺寸分布，大约 1-3% 的总碎片是由 4 至 6 毫米的滴之间的碰撞破碎产生的。
Collision-induced water drop breakup in a vertical wind tunnel was observed using a high speed camera for interactions between larger drop sizes (up to 7 mm diameter) than have previously been experimentally observed. Three distinct collisional breakup types were observed and the drop size distributions from each were analysed for comparison with predictions of fragment distributions from larger drops by two sets of established breakup parameterisations. The observations showed some similarities with both parameterisations but also some marked differences for the breakup types that could be compared, particularly for fragments 1 mm and smaller. Modifications to the parameterisations are suggested and examined. Presented is also currently the largest dataset of bag breakup distributions observed. Differences between this and other experimental research studies and modelling parameterisations, and the associated implications for interpreting results are discussed. Additionally, the stochastic coalescence and breakup equation was solved computationally using a breakup parameterisation, and the evolving drop-size distribution for a range of initial conditions was examined. Initial cloud liquid water content was found to have the greatest influence on the resulting distribution, whereas initial drop number was found to have relatively little influence. This may have implications when considering the effect of aerosol on cloud evolution, raindrop formation and resulting drop size distributions. Calculations presented show that, using an ideal initial cloud drop-size distribution, similar to 1-3% of the total fragments are contributed from collisional breakup between drops of 4 and 6 mm.