Dutta P, Beskok A
Microfluidics Laboratory, Mechanical Engineering Department, Texas A&M University, College Station 77843-3123, USA.
Anal Chem. 2001 May 1;73(9):1979-86. doi: 10.1021/ac001182i.
Analytical results for the velocity distribution, mass flow rate, pressure gradient, wall shear stress, and vorticity in mixed electroosmotic/pressure driven flows are presented for two-dimensional straight channel geometry. We particularly analyze the electric double-layer (EDL) region near the walls and define three new concepts based on the electroosmotic potential distribution. These are the effective EDL thickness, the EDL displacement thickness, and the EDL vorticity thickness. We show that imposing Helmholtz-Smoluchowski velocity at the edge of the EDL as the velocity matching condition between the EDL and the bulk flow region is incomplete under spatial bulk flow variations across the finite EDL. However, the Helmholtz-Smoluchowski velocity can be used as the appropriate slip velocity on the wall. We discuss the limitations of this approach in satisfying the global conservation laws.
给出了二维直通道几何结构中混合电渗/压力驱动流的速度分布、质量流率、压力梯度、壁面剪应力和涡度的分析结果。我们特别分析了壁面附近的电双层（EDL）区域，并基于电渗势分布定义了三个新概念。它们分别是有效EDL厚度、EDL位移厚度和EDL涡度厚度。我们表明，在有限EDL上存在空间总体流变化的情况下，将EDL边缘处的亥姆霍兹-斯莫卢霍夫斯基速度作为EDL与总体流区域之间的速度匹配条件是不完整的。然而，亥姆霍兹-斯莫卢霍夫斯基速度可以用作壁面上合适的滑移速度。我们讨论了这种方法在满足全局守恒定律方面的局限性。
