气体聚焦的液体流动：喷射、滴落和再循环

The nonlinear states of viscous capillary jets confined in the axial direction

We report an experimental and theoretical study of the global stability and nonlinear dynamics of vertical jets of viscous liquid confined in the axial direction due to their impact on a bath of the same liquid. Previous works demonstrated that in the absence of axial confinement the steady liquid thread becomes unstable due to an axisymmetric global mode for values of the flow rate, $Q$, below a certain critical value, $Q_c$, giving rise to oscillations of increasing amplitude that finally lead to a dripping regime (Sauter & Buggisch, J. Fluid Mech., 2005; Rubio-Rubio et al., J. Fluid Mech., …

界面滴漏：产生单分散液体透镜

Interfacial dripping faucet: generating monodisperse liquid lenses

本文提出界面滴漏现象，通过粘性液体沿不混溶弯月面滑下并周期性断离产生单分散液体透镜，类比单相滴漏并用铺展系数替代表面张力，为界面乳液动力学研究开辟前景。

击败喷射制度

Beating the jetting regime

我们数值研究了微毛细管并流装置中射流和液滴的动力学。共流流遇到不同的流动状态，包括滴落、喷射。采用水平集/有限元轴对称数值模拟，我们研究了受流量扰动的射流破碎动力学。的未扰动射流的宽度的标度律，并与现有的实验结果以及数值测量。然后，我们表明，引入一个正弦扰动的内部流体流速可以促进分裂的流体在制度，通常观察到的射流。此外，流速扰动导致对所得液滴的尺寸和频率的良好控制。使用理论建模，我们提供了一个标准，以确定最佳的频率打破射流。我们还推导出定标律，以确定封装在乳液液滴中的内部流体的体积作为频率的函数，并估计作为扰动幅度的函数的射流破裂的距离。这些标度律与数值模拟的结果吻合得很好。我们的工作提出了一种新的方法，并提供了指导原则，打破液体射流的情况下，滴水是难以实现的。

Transition from bubbling to jetting in a co-axial air-water jet

In this Brief Communication we study experimentally the flow regimes that appear in co-axial air-water jets discharging into a stagnant air atmosphere and we propose a simple explanation for their occurrence based on linear, local, spatiotemporal stability theory. In addition to the existence of a periodic bubbling regime for low enough values of the water-to-air velocity ratio, $u=u_w/u_a$, our experiments revealed the presence of a jetting regime for velocity ratios higher than a critical one, $u_c$. In the bubbling regime, bubbles form periodically from the tip of an air ligament whose leng…

无条件喷射

Unconditional jetting

分散到另一不混溶相中的流体的毛细管喷射通常受到临界毛细管数的限制，临界毛细管数是雷诺数和流体性质比的函数。当小扰动$v^*_-$沿喷流的最小传播速度（边缘稳定速度）为零时，设定临界条件。在这里，我们确定并描述了高技术相关性的参数区域，其中$v^*_- > 0$和射流总是超临界的，与分散的液体流速无关：在这些相对较宽的区域内，射流不经历通常的滴注-喷射过渡，使得射流可以任意地薄（产生任何可接受的小尺寸的液滴），或者发出的流速可以任意地小。在这项工作中，我们提供了说明性的分析研究的渐近情况下，可忽略不计的惯性力和主导。在后一种情况下，需要非零的射流表面速度，对于所有给定的波数，轴对称扰动波向下游“冲浪”，而液体主体可以保持静止。在前一种情况下（意味着小雷诺流），我们发现，射流剖面小斜率是有限的临界值，不同的实验支持我们的预测。

Universal self-scalings in a micro-co-flowing

On hypothesis of self-scaling co-flows in tapered rectanglar PMMA micro-channels for producing mono-dispersed liquid cells, universal scalings through all liquid detaching regimes are found under a self-similarity frame. Pan-dripping and Pan-jetting regimes are calculated clearly to border at the Weber number approximately $1$ and the capillary number approximately $0.28$ by machine learning classification. The sizes, as well as detaching frequencies, of liquid cells in different flow regimes behave at the same manner and submit to the same law, and such highly consistent behaviors breaking th…

多相粒子法在液体射流雾化与破碎研究中的应用

Application of Multiphase Particle Methods in Atomization and Breakup Regimes of Liquid Jets

采用多相光滑粒子流体动力学（SPH）方法对射流破碎现象进行了研究。结果表明，该方法能够很好地捕捉不同的射流破碎特性。在从滴注到喷射的过渡过程中获得的临界韦伯数的值与文献中的可用值非常匹配。射流破碎长度也与几个经验相关性很好地吻合。SPH作为一种快速的CFD求解器，在射流破碎分析中的成功应用有助于加速这一现象的数值研究。

Raydrop : a universal droplet generator based on a non-embedded co-flow-focusing

Most commercial microfluidic droplet generators rely on the planar flow-focusing configuration implemented in polymer or glass chips. The planar geometry, however, suffers from many limitations and drawbacks, such as the need of specific coatings or the use of dedicated surfactants, depending on the fluids in play. On the contrary, and thanks to their axisymmetric geometry, glass capillary-based droplet generators are a priori not fluid-dependent. Nevertheless, they have never reached the market because their assembly requires art-dependent and not scalable fabrication techniques. Here we pres…

共流装置中流体流动的稳定性分析

Stability analysis of the flow in a coflowing device

共流装置中流体稳定性分析表明，喷射流在锥形膜 tapering 之前不稳定，线性稳定性分析无法预测多分散滴落的参数条件，瞬态模拟显示初始扰动对喷射流破裂有显著影响。

CLIP：一种用于界面现象研究的CUDA加速格子玻尔兹曼框架及其在液体射流模拟中的应用

CLIP: A CUDA-Accelerated Lattice Boltzmann Framework for Interfacial Phenomena with Application to Liquid Jet Simulations

本研究提出CUDA加速的相场格子玻尔兹曼框架CLIP，采用WMRT碰撞算子提升稳定性与精度，经多基准验证后应用于液体射流模拟，准确捕捉流态转变并得到临界韦伯数，为多相流界面研究提供高效易用工具。