微通道液滴生成的格子玻尔兹曼数值模拟

液滴微流控被广泛应用于化学、生物、医学等领域。通过探索微纳米尺度下 液体的流动规律、液滴生成和控制机制，可以实现液滴在微流控芯片中的精确控 制和应用。研究微液滴生成，不仅可以推动微流控技术的发展，也可以为化学、生 物、医学等领域提供理论支撑。本文基于格子玻尔兹曼方法和相场方法，研究了 不同微通道结构下的液滴生成特性，分析了不同因素对液滴生成的影响。

首先，本文在静态条件下模拟了液滴的拉普拉斯定律，以及液滴与壁面的接 触角，在动态条件模拟了液滴的融合以及剪切流下液滴的变形，模拟结果正确地 描述了界面张力、壁面润湿条件以及两相界面的演化，验证了计算模型的准确性 和可靠性。

其次，本文对微通道内液滴生成特性进行分析，发现两相粘度比对液滴的影 响很小, 而连续相毛细数是液滴生成的关键。当毛细数比较小时（Ca = 0.005），通 道内能稳定地生成尺寸均一的液滴，并且液滴的相对长度随着毛细数的增大而增 大。当毛细数比较大时（Ca = 0.05）, 液滴生成机制发生改变，液滴生成的稳定性 和均一性被破坏。

同时，本文在研究壁面润湿性对液滴生成的影响时发现，T 型微通道中液滴的 生成取决于通道壁面接触角 𝜃 的大小。当接触角大于 120∘ 时，液滴尺寸变化较小 （𝜃 = 120∘ 与 𝜃 = 180∘ 下液滴相对长度差异为 7%）；当接触角小于 60∘ 时，液滴 无法正常生成。而在十字型微通道中，接触角较小时也能正常生成液滴，液滴尺 寸随接触角呈线性变化。

最后，本文探讨了因为制造或者控制误差造成的异构通道对液滴生成的影响。 数值模拟结果显示当十字型微通道的分散相轴线与主通道轴线的偏心距增加时， 主导液滴生成的作用力会由正应力转变为粘性切应力。当偏心距小于主通道宽度 𝑤𝑐 的一半时，液滴的相对长度随偏心距的增加而增加；当偏心距大于 0.5𝑤𝑐 后，液 滴尺寸变化不明显（偏心距为 0.5𝑤𝑐 和 2𝑤𝑐 的液滴相对长度差异为 1%）。通过单 独减小连续相一端的流道宽度，能实现毛细数较大时液滴的正常生成，液滴相对 长度随宽度比的减小而线性减小。

本文通过格子玻尔兹曼方法研究了毛细数、壁面接触角、通道结构等因素对 液滴生成的影响，发现可以通过调整这些参数来控制液滴生成的频率和尺寸。这 些研究结果对于微流控领域的设计和应用具有重要的理论指导意义，可以帮助改善微流控芯片中的液滴生成和控制效果，从而推动微流控技术的应用发展。

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