Edwards Andrew M J, Ruiz-Gutiérrez Élfego, Newton Michael I, McHale Glen, Wells Gary G, Ledesma-Aguilar Rodrigo, Brown Carl V
SOFT Group, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.
Institute for Multiscale Thermofluids, School of Engineering, University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh, EH9 3FB, UK.
Sci Rep. 2021 Apr 14;11(1):8120. doi: 10.1038/s41598-021-87549-5.
The breakup of a slender filament of liquid driven by surface tension is a classical fluid dynamics stability problem that is important in many situations where fine droplets are required. When the filament is resting on a flat solid surface which imposes wetting conditions the subtle interplay with the fluid dynamics makes the instability pathways and mode selection difficult to predict. Here, we show how controlling the static and dynamic wetting of a surface can lead to repeatable switching between a toroidal film of an electrically insulating liquid and patterns of droplets of well-defined dimensions confined to a ring geometry. Mode selection between instability pathways to these different final states is achieved by dielectrophoresis forces selectively polarising the dipoles at the solid-liquid interface and so changing both the mobility of the contact line and the partial wetting of the topologically distinct liquid domains. Our results provide insights into the wetting and stability of shaped liquid filaments in simple and complex geometries relevant to applications ranging from printing to digital microfluidic devices.
由表面张力驱动的细长液体细丝的破裂是一个经典的流体动力学稳定性问题，在许多需要细液滴的情况下都很重要。当细丝放置在施加润湿条件的平坦固体表面上时，与流体动力学的微妙相互作用使得不稳定性路径和模式选择难以预测。在这里，我们展示了如何控制表面的静态和动态润湿，从而在电绝缘液体的环形薄膜和局限于环形几何形状的尺寸明确的液滴模式之间实现可重复的切换。通过介电泳力选择性地极化固液界面处的偶极子，从而改变接触线的迁移率和拓扑不同的液体域的部分润湿性，实现了通往这些不同最终状态的不稳定性路径之间的模式选择。我们的结果为与从打印到数字微流控设备等应用相关的简单和复杂几何形状中成形液体细丝的润湿和稳定性提供了见解。
