Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
J Colloid Interface Sci. 2012 Apr 15;372(1):207-11. doi: 10.1016/j.jcis.2012.01.044. Epub 2012 Feb 1.
In this paper, we conducted numerical simulation of the electroosmotic flow in a column of an aqueous solution surrounded by an immiscible liquid. While governing equations in this case are the same as that in the electroosmotic flow through a microchannel with solid walls, the main difference is the types of interfacial boundary conditions. The effects of electric double layer (EDL) and surface charge (SC) are considered to apply the most realistic model for the velocity boundary condition at the interface of the two fluids. Effects on the flow field of ς-potential and viscosity ratio of the two fluids were investigated. Similar to the electroosmotic flow in microchannels, an approximately flat velocity profile exists in the aqueous solution. In the immiscible fluid phase, the velocity decreases to zero from the interface toward the immiscible fluid phase. The velocity in both phases increases with ς-potential at the interface of the two fluids. The higher values of ς-potential also increase the slip velocity at the interface of the two fluids. For the same applied electric field and the same ς-potential at the interface of the two fluids, the more viscous immiscible fluid, the slower the system moves. The viscosity of the immiscible fluid phase also affects the flatness of the velocity profile in the aqueous solution.
本文对水溶液在不可混溶液体包围的圆管中电渗流进行了数值模拟。虽然这种情况下的控制方程与固体壁微通道中电渗流的方程相同，但主要区别在于界面边界条件的类型。考虑了双电层 (EDL) 和表面电荷 (SC) 的影响，以应用最真实的模型来施加在两种流体界面处的速度边界条件。研究了 ζ-电势和两种流体的粘度比对流动场的影响。与微通道中的电渗流类似，水溶液中存在近似平坦的速度分布。在不可混溶的流体相中，速度从界面向不可混溶的流体相逐渐减小到零。两种流体界面处的 ζ-电势越高，速度也越高。在相同的外加电场和两种流体界面处相同的 ζ-电势下，不可混溶流体的粘度越高，系统的运动速度越慢。不可混溶流体相的粘度也会影响水溶液中速度分布的平坦度。
