关于动态湍流中气泡相互作用的尺度：理论、数值和实验研究
On the scaling of bubble interactions in dynamic turbulence: theoretical, numerical, and experimental study
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中文总结 AI 辅助
研究高雷诺数下稀气泡衰变均匀各向同性湍流，通过理论、数值模拟和实验，揭示气泡相互作用规律，包括湍动能和耗散率的幂律衰减、欣泽尺度变化及不同区域气泡行为，确定欣泽尺度漂移机制并为相关模型提供指导。
中文摘要 AI 辅助
本研究利用理论、直接数值模拟和实验，研究了高雷诺数下稀气泡衰变均匀各向同性湍流。湍动能和耗散率遵循幂律衰减，而气泡群相对于不断演变的欣泽尺度重新组织。当耗散足够快地衰减时，欣泽尺度比特征气泡直径增长得更快，使气泡群从超欣泽尺寸向亚欣泽尺寸转变。系统经历一个合并占主导但破裂仍活跃的混合区域，随后是纯合并区域。混合区域中的残余破裂增加了小气泡的数量并增强了合并，导致特征气泡尺寸更快增长。稀气泡湍流的直接数值模拟显示衰减指数接近单相湍流，且气泡尺寸分布相对于欣泽尺度向更小直径移动。在转变之前，分布呈现与毛细作用和惯性破裂相关的两个幂律范围；转变之后，它接近单一的毛细主导尺度。理论和直接数值模拟预测了混合和纯合并区域中气泡直径的不同增长规律，以及数密度、界面面积和合并率的相应尺度。这些预测在更高雷诺数的空间发展泵驱动气泡管道流中得到进一步评估。尽管存在限制、不均匀性和壁面产生，但测量趋势与基于理论和直接数值模拟的尺度一致。结果确定欣泽尺度漂移是理想和实际衰变湍流中气泡相互作用的组织机制，并为群体平衡和界面面积传输模型提供指导。
英文摘要
This study investigates dilute bubbly decaying homogeneous isotropic turbulence at high Reynolds number using theory, direct numerical simulation, and experiments. The turbulent kinetic energy and dissipation rate follow power-law decay, while the bubble population reorganizes relative to the evolving Hinze scale. When the dissipation decays sufficiently rapidly, the Hinze scale grows faster than the characteristic bubble diameter, driving the population from super-Hinze toward sub-Hinze sizes. The system passes through a mixed regime in which coalescence dominates but breakup remains active, followed by a pure-coalescence regime. Residual breakup in the mixed regime increases the number of small bubbles and enhances coalescence, leading to faster growth of the characteristic bubble size. DNS of dilute bubble-laden turbulence shows decay exponents close to single-phase turbulence and a bubble-size distribution that shifts toward smaller diameter relative to the Hinze scale. Before the transition, the distribution exhibits two power-law ranges associated with capillary effects and inertial breakup; after the transition, it approaches a single capillary-dominated scaling. Theory and DNS predict distinct growth laws for bubble diameter in the mixed and pure-coalescence regimes, together with corresponding scalings for number density, interfacial area, and coalescence rate. These predictions are further assessed in a spatially developing pump-driven bubbly duct flow at higher Reynolds number. Despite confinement, inhomogeneity, and wall production, the measured trends agree with the theoretical and DNS-based scalings. The results identify Hinze-scale drift as the organizing mechanism for bubble interactions in both idealized and practical decaying turbulent flows, and provide guidance for population-balance and interfacial-area-transport models.
