脉冲毛细射流产生的液滴尺寸：无下限截断的指数分布
Droplet sizes from impulsive capillary jets: an exponential distribution with no lower cut-off
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中文总结 AI 辅助
该研究发现脉冲毛细射流产生的液滴尺寸无下限截断，服从由空穴半径设定尺度的指数分布，加载方式而非仅流体决定喷雾形状，修正了此前认为液滴尺寸有粘性毛细长度下限的结论。
中文摘要 AI 辅助
塌陷的空穴会抛出一股韧带，该韧带碎裂成一系列液滴，其尺寸通常被设定为粘性毛细长度ℓ_μ=μ²/ρσ的固定倍数下限。我们证明不存在这样的下限，其原因比单一参数的命运更具普遍性：脉冲射流本身没有特征长度。控制每次颈缩的相似解不包含任何特征长度，拉伸与迭代卫星液滴的级联也不会引入特征长度，且ℓ_μ属于奇点而非液滴。基于该过程构建的尺寸分布只能从一处继承尺度，即发射射流的空穴。对受限与非受限气泡破裂的计算证实了这一点：它们呈现的下限是网格施加的，而非流体的属性，且只要网格分辨率低于ℓ_μ，就能发现液滴。统计得到的独特发射液滴服从指数分布，其单一尺度由空穴半径设定，与事件的剧烈程度及周围液体量均无关。指数分布是与给定均值兼容的结构最简洁的统计结果，因此碎裂过程仅保留空穴的尺寸，而不保留其母体的其他记忆。持续拉伸确实会保留此类记忆，印刻母体韧带的波纹，产生韧带介导碎裂所报道的峰形、类伽马分布。加载方式而非仅流体，决定了喷雾的形状。
英文摘要
A collapsing cavity throws up a ligament, which fragments into a train of droplets whose sizes are commonly given a lower bound at a fixed multiple of the viscocapillary length $\ell_μ=μ^2/ρσ$. We show that no such bound exists, for a reason more general than the fate of one parameter: an impulsive jet possesses no length of its own. The similarity solutions that govern each pinch contain none, the cascade of stretching and iterated satellites introduces none, and $\ell_μ$ belongs to the singularity rather than to the droplets. A size distribution built on such a process can inherit a scale from one place only, the cavity that launched the jet. Computations of bubble bursting, confined and unconfined, bear this out. The floor they display is the one the mesh imposes, not a property of the fluid, and wherever the mesh looks below $\ell_μ$ it finds droplets. The census of unique emitted droplets is exponential, with a single scale set by the cavity radius, indifferent both to how vigorous the event is and to how much liquid surrounds it. An exponential is the least structured census compatible with a prescribed mean, so the fragmentation keeps the size of the cavity and no other memory of its parent. Sustained stretching does keep such a memory, imprinting the corrugation of the parent thread and yielding the peaked, gamma-like distributions reported for ligament-mediated fragmentation. The manner of loading, and not the fluid alone, selects the shape of a spray.
发表机构
- Universidad de Sevilla（塞维利亚大学）
机构由 AI 辅助整理，请以论文原文为准。
