Hysteresis in spreading and retraction of liquid droplets on parallel fiber rails
Hysteresis in spreading and retraction of liquid droplets on parallel fiber rails
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DOI：
10.1039/d1sm00126d
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发表时间：
2021-04-21
期刊：
影响因子：
3.4
通讯作者：
Schiller, Ulf D.
中科院分区：
文献类型：
--
作者：
Wang, Fang;Schiller, Ulf D.
液体在纤维上的润湿和铺展在许多自然和人工过程中都会发生。与平面衬底不同，附着在一根或多根纤维上的液滴可以呈现几种不同的形状，这取决于液体体积、纤维大小和距离等几何参数。本文用格子Boltzmann方法模拟了平行圆柱形纤维上液滴的形态。我们研究了由于沉积在纤维上的初始球形液滴的扩散和纤维之间沉积的初始液柱的回缩而产生的最终形状。我们观察到三种可能的平衡构型：桶形液滴、液滴桥和液柱。我们确定了不同纤维间距和液体体积的完整形态图，并找到了横跨柱状区域和液滴区域的双稳区域。我们进一步提出了一种模拟协议，允许人们探测不同形状之间的转变的滞后。这些结果提供了与纤维上液滴形状转换相关的能量和力的洞察，可用于开发基于纤维的材料和用于小规模操纵液体的微流体系统。
Wetting and spreading of liquids on fibers occur in many natural and artificial processes. Unlike on a planar substrate, a droplet attached to one or more fibers can assume several different shapes depending on geometrical parameters such as liquid volume and fiber size and distance. This paper presents lattice Boltzmann simulations of the morphology of liquid droplets on two parallel cylindrical fibers. We investigate the final shapes resulting from spreading of an initially spherical droplet deposited on the fibers and from retraction of an initial liquid column deposited between the fibers. We observe three possible equilibrium configurations: barrel-shaped droplet, droplet bridges, and liquid columns. We determine the complete morphology diagram for varying inter-fiber spacings and liquid volumes and find a region of bistability that spans both the column regime and the droplet regime. We further present a simulation protocol that allows one to probe the hysteresis of transitions between different shapes. The results provide insights into energies and forces associated with shape transformations of droplets on fibers that can be used to develop fiber-based materials and microfluidic systems for manipulation of liquids at a small scale.