标题： 锥形共流中气泡闭合和内部射流发射的自相似性 显示英文标题

标题： Self-scalings of bubble pinch-off and inner jet emitting in a tapered co-flow

摘要： 本研究系统地探讨了在汇聚同轴微通道中亚毫米级气泡射流生成的形成机制和尺度律。实验观察揭示了单分散气泡形成的四个演化阶段：生长、颈部化、脱离和稳定。通过颈部破裂动力学建模，我们证明了喷嘴插入长度（$x$）和收敛角（$\alpha$）的耦合效应主导了颈部宽度的演化，在几何构型中表现出普遍的幂律尺度特性。关键的是，颈部界面在剪切作用下的时空演化展示了自相似性：时间演化相对于剩余时间（$T-t$）遵循幂律衰减，而空间尺度与特征尺寸（$W_\text{local}$）通过幂律关系相关联。多阶段数学模型成功描述了这种自相似界面行为，证实了它们的预测有效性。此外，我们确定了气泡射流生成的核心机制为通过前端拉伸和后端挤压相互作用表征的汇聚区域流动场的动力学调制。实验验证表明在多物理场耦合作用下不同流动状态下射流速度演化一致，确立了控制汇聚微通道结构中流动结构和动态行为的几何相似性原理。 显示英文摘要

摘要： This study systematically investigates the formation mechanisms and scaling laws governing sub-millimeter bubble-jet generation in convergent coaxial microchannels. Experimental observations reveal four distinct evolutionary stages in monodisperse bubble formation: growth, necking, detachment, and stabilization. Through necking rupture dynamics modeling, we demonstrate that the coupled effects of nozzle insertion length ($x$) and convergence angle ($\alpha$) dominate neck width evolution, exhibiting universal power-law scaling across geometric configurations. Crucially, the spatiotemporal evolution of necking interfaces under shear demonstrates self-similarity: temporal evolution follows a power-law decay with respect to remaining time ($T-t$), while spatial scaling correlates with characteristic dimension $W_\text{local}$ through power-law relationships. Multi-stage mathematical models successfully describe this self-similar interfacial behavior, confirming their predictive validity. Furthermore, we identify the core mechanism of bubble-jet formation as dynamic modulation through convergent zone flow fields characterized by front-end stretching and rear-end squeezing interactions. Experimental validation shows consistent jet velocity evolution across flow regimes under multiphysics coupling, establishing geometric similarity principles governing flow structures and dynamic behaviors in convergent microchannel architectures.