考虑流动电位的微米/纳米毛细管单相渗流模式

Single-phase flow model in micro/nanoscale capillaries considering streaming potential

流体在多孔介质中流动时,由于固-液界面扩散双电层的存在,流体的流动会产生流动电位现象,而流动电位会反过来对流体在多孔介质中的流动造成影响。从微米和纳米尺度,利用圆形、正方形和三角形截面毛细管模型,采用有限元数值求解方法,研究了在不同毛细管尺寸下,流动电位对毛细管单相流体渗流模式的影响,得到了考虑流动电位情况下不同尺寸三角形截面毛细管传导率和其形状因子的关系,并研究了在不同毛细管尺寸条件下,考虑流动电位对流体流动的影响后外加压力梯度与流体流量之间的关系。研究结果表明,由于流动电位对流体流动的影响,当毛细管尺寸与扩散双电层厚度相当时,流动电位会对流体在毛细管中的流动产生显著影响,流体的流动阻力增加,毛细管传导率减小,但是毛细管中的流体流量与压力梯度仍然保持线性关系。

Due to the presence of electric double layer at the solid-liquid interface,fluid flow in porous media can give rise to streaming potential which in turn influences the fluid flow.In this study,the impact of streaming potential on fluid flow is investigated at the micro-/nanoscale by resolving different sizes of capillary models of circular,square,and triangular cross sections using finite element numerical method.The relationships between conductivities in triangular capillaries of different sizes and their corresponding shape factors are examined by considering streaming potential.Additionally,the relationship between flow rate in capillaries of different sizes and their external pressure gradients are investigated.Results show that streaming potential strongly impacts fluid flow in capillaries when the size of the capillary is comparable to the thickness of the electric double layer.Due to the impact of streaming potential,flow resistance of the fluid increases while the conductivities in capillaries decrease.However,the relationship between flow rate and pressure gradient in capillaries remains linear.