级联驱动的衰减湍流中的破碎-聚并转变
Cascade-driven fragmentation-aggregation transitions in decaying turbulence
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中文总结 AI 辅助
本研究提出级联控制框架，揭示衰减湍流中Hinze尺度动态变化驱动破碎-聚并转变，预测临界指数5/3，并通过数值模拟和实验验证，取代传统瞬时准则。
中文摘要 AI 辅助
在衰减湍流中，湍流级联并非仅仅是破碎的被动背景，而是一个演化的稳定性边界，动态地选择破碎-聚并路径。随着湍流衰减，Hinze尺度扫过气泡尺寸分布，逐步消除可破碎群体，并驱动从混合破碎-聚并状态向自维持的纯聚并状态的转变。我们的模型预测了临界湍流衰减指数$m=5/3$、瞬态混合破碎-聚并状态以及具有普适聚并危险的后期纯聚并状态。有趣的是，瞬态破碎起到催化剂作用，相对于纯聚并，放大了混合状态下的气泡增长。我们对衰减均匀各向同性湍流的直接数值模拟以及高雷诺数管道流动实验的结果，在根据实测衰减率表示时，与模型预测吻合。这些结果用非平衡、级联控制的湍流破碎与聚集框架取代了传统的瞬时Hinze准则。
英文摘要
In decaying turbulence, the turbulent cascade is not merely a passive background for breakup but an evolving stability boundary that dynamically selects the fragmentation-aggregation pathway. As turbulence decays, the Hinze scale sweeps through the bubble-size distribution, progressively eliminating the breakable population and driving a transition from a mixed breakup-coalescence regime to a self-sustaining pure-coalescence state. Our model predicts a critical turbulence decay exponent $m=5/3$, a transient mixed breakup-coalescence regime, and a late-stage pure-coalescence state with a universal coalescence hazard. Interestingly, the transient breakup acts as a catalyst that amplifies mixed-regime bubble growth relative to pure coalescence. Results from our direct numerical simulations of decaying homogeneous isotropic turbulence as well as high-Reynolds-number duct-flow experiments collapse onto the model predictions when expressed in terms of the measured decay rate. These results replace the conventional instantaneous Hinze criterion with a non-equilibrium, cascade-controlled framework for turbulent fragmentation and aggregation.
发表机构
- Georgia Institute of Technology（佐治亚理工学院）
机构由 AI 辅助整理，请以论文原文为准。
