Davison S M, Sharp K V
Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 127 Reber Building, University Park, PA 16802, USA.
J Colloid Interface Sci. 2006 Nov 1;303(1):288-97. doi: 10.1016/j.jcis.2006.07.063. Epub 2006 Jul 28.
The bounded electrophoretic motion of a cylindrical particle in a circular cylindrical microchannel is explored for two cases: (1) the particle is located on the centerline of a channel (concentrically), with a symmetric wall boundary condition since gap width is constant throughout; and (2) the particle is at an eccentric location in the channel, with an asymmetric boundary condition set by the walls. The objective is to determine the effect of different boundary conditions, geometries, and physical properties on the velocity and orientation of the cylinder with respect to the boundary. A theoretical model for the motion of the cylinder is presented and the problem is solved numerically. The steady-state simulations show that the velocity of the cylinder is reduced at small gap widths for the concentric case, but the velocity is increased at small gap widths for the eccentric case. When the cylinder is angled with respect to the horizontal in the symmetric case or is near the boundary in the asymmetric case, vertical and rotational components of velocity are predicted. In such cases, transient simulations are appropriate for most accurately representing particle motion. Two such simulations are included herein and show both horizontal and vertical translation plus rotation of the particle as a function of time.
（1）颗粒位于通道的中心线上（同心），由于间隙宽度在整个通道中保持恒定，因此具有对称的壁边界条件；（2）颗粒位于通道中的偏心位置，由壁设置非对称边界条件。目的是确定不同的边界条件、几何形状和物理性质对圆柱体相对于边界的速度和方向的影响。提出了圆柱体运动的理论模型，并对该问题进行了数值求解。稳态模拟表明，在同心情况下，间隙宽度较小时圆柱体的速度会降低，但在偏心情况下，间隙宽度较小时速度会增加。当圆柱体在对称情况下相对于水平方向倾斜或在非对称情况下靠近边界时，可以预测速度的垂直和旋转分量。在这种情况下，瞬态模拟最适合精确表示颗粒运动。本文包含了两个这样的模拟，展示了颗粒的水平和垂直平移以及旋转随时间的变化。
