Capillary flow of evaporating liquid solutions in open rectangular microchannels
Capillary flow of evaporating liquid solutions in open rectangular microchannels
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DOI：
10.1017/jfm.2022.140
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发表时间：
2022-03
影响因子：
3.7
通讯作者：
Panayiotis Kolliopoulos;Krystopher S. Jochem;L. Francis;Satish Kumar
中科院分区：
文献类型：
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作者：
Panayiotis Kolliopoulos;Krystopher S. Jochem;L. Francis;Satish Kumar
摘要 液体的毛细管流动在许多应用中发挥着关键作用，包括芯片实验室设备、热管和印刷电子制造。开放的矩形微通道经常出现在这些应用中，由于没有顶部，导致复杂的自由表面形态和蒸发。在这项工作中，我们开发了一个基于润滑理论和动力学限制蒸发的理论模型，以检查连接到圆形储液器的开放矩形微通道中蒸发液体溶液的毛细管流动。该模型考虑了复杂的自由表面形态、溶剂蒸发、由于溶质浓度和温度梯度以及有限尺寸储层效应而导致的马兰戈尼流动。由于溶剂蒸发和溶质传输，预计纯液体和液体溶液之间的流动行为存在显着差异。研究发现，马兰戈尼流可以在溶剂蒸发后促进更均匀的溶质沉积模式。弯液面位置演化的模型预测与先前在蒸发情况下聚乙烯醇水溶液的毛细管流动实验非常一致。该模型揭示了实验中蒸发影响弯液面位置的主要机制是粘度随溶质浓度的增加。
Abstract Capillary flow of liquids plays a key role in many applications including lab-on-a-chip devices, heat pipes and printed electronics manufacturing. Open rectangular microchannels often appear in these applications, with the lack of a top resulting in a complex free-surface morphology and evaporation. In this work we develop a theoretical model based on lubrication theory and kinetically limited evaporation to examine capillary flow of evaporating liquid solutions in open rectangular microchannels connected to circular reservoirs. The model accounts for the complex free-surface morphology, solvent evaporation, Marangoni flows due to gradients in solute concentration and temperature and finite-size reservoir effects. Significant differences are predicted in flow behaviour between pure liquids and liquid solutions due to solvent evaporation and solute transport. Marangoni flows are found to promote more uniform solute deposition patterns after solvent evaporation. Model predictions of meniscus position evolution are in good agreement with prior capillary-flow experiments of aqueous poly(vinyl alcohol) solutions in the presence of evaporation. The model reveals that the principal mechanism through which evaporation influences the meniscus position in the experiments is the increase in viscosity with solute concentration.