Department of Chemistry , University of Washington , Box 351700, Seattle , Washington 98195 , United States.
Department of Urology , University of Washington School of Medicine , Seattle , Washington 98105 , United States.
Langmuir. 2019 Aug 13;35(32):10667-10675. doi: 10.1021/acs.langmuir.9b01456. Epub 2019 Aug 1.
Open capillary flows are increasingly used in biotechnology, biology, thermics, and space science. So far, the dynamics of capillary flows has been studied mostly for confined channels. However, the theory of open microfluidics has considerably progressed during the last years, and an expression for the travel distance has been derived, generalizing the well-known theory of Lucas, Washburn, and Rideal. This generalization is based on the use of the average friction length and generalized Cassie angle. In this work, we successively study the spontaneous capillary flow in uniform cross section open rounded U-grooves-for which methods to determine the friction lengths are proposed-the flow behavior at a bifurcation, and finally flow in a simple-loop network. We show that after a bifurcation, the Lucas-Washburn-Rideal law needs to be adapted and the relation between the travel distance and time is more complicated than the square root of time dependency.
开式毛细流动在生物技术、生物学、热学和空间科学中得到了越来越多的应用。到目前为止，毛细流动的动力学主要针对受限通道进行了研究。然而，近年来开式微流理论取得了相当大的进展，已经推导出了一个行程距离的表达式，将著名的 Lucas、Washburn 和 Rideal 理论进行了推广。这种推广基于使用平均摩擦长度和广义 Cassie 角。在这项工作中，我们依次研究了均匀横截面开式圆形 U 形槽中的自发毛细流动（为此提出了确定摩擦长度的方法）、在分叉处的流动行为，最后是在简单的环形网络中的流动。我们表明，在分叉之后，需要适应 Lucas-Washburn-Rideal 定律，行程距离与时间之间的关系比时间依赖性的平方根更为复杂。
