论文标题
小涡流中的湍流破碎
Fragmentation in turbulence by small eddies
论文作者
论文摘要
从空气气体交换，石油污染到生物反应器，湍流中气泡/滴的无处不在碎片化是通过依靠1950年代以来经典的Kolmogorov-Hinze范式来建模的。该框架假设气泡/滴水仅被相同尺寸的涡流打破，即使湍流以其广泛的鳞片而闻名。在这里，通过设计一个可以在各种尺寸的物理和清晰散开涡流的实验，我们报告了挑战这一假设的实验证据，并表明气泡被子尺度的涡流优先损坏。我们的工作还强调，碎片不能仅通过压力标准或韦伯数来量化。不同时间尺度之间的竞争同样重要。与其在自己的尺度上流动缓慢而持久地延伸，不如在短时间内通过一系列强烈的局部变形而在湍流中碎裂气泡。
From air-sea gas exchange, oil pollution, to bioreactors, the ubiquitous fragmentation of bubbles/drops in turbulence has been modelled by relying on the classical Kolmogorov-Hinze paradigm since the 1950s. This framework hypothesizes that bubbles/drops are broken solely by eddies of the same size, even though turbulence is well known for its wide spectrum of scales. Here, by designing an experiment that can physically and cleanly disentangle eddies of various sizes, we report the experimental evidence to challenge this hypothesis and show bubbles are preferentially broken by the sub-bubble-scale eddies. Our work also highlights that fragmentation cannot be quantified solely by the stress criterion or the Weber number; The competition between different time scales is equally important. Instead of being elongated slowly and persistently by flows at their own scales, bubbles are fragmented in turbulence by small eddies via a burst of intense local deformation within a short time.
