Sato Norikazu, Kawashima Daisuke, Takei Masahiro
Sensing & Process Solution Division, JFE Techno-Research Corporation, Kanagawa, 210-0855, Japan.
Graduate School of Science and Engineering, Chiba University, Chiba, 263-8522, Japan.
Sci Rep. 2021 Jan 28;11(1):2585. doi: 10.1038/s41598-021-82259-4.
Three-dimensional ion and particle concentrations under hydrodynamic focusing in a Y-shaped square microchannel are numerically simulated to clarify the decrease of the ion concentration along the flow direction within the focused particle stream. The simulation model is theoretically governed by the laminar flow and advection-diffusion equations. The governing equations are solved by the finite volume method. The ion and particle concentration distributions at five cross sections after the confluence of the branch channels are analyzed in 30 cases in which the sheath to sample flow rate ratio Q/Q and the Reynolds number Re are varied as parameters. The results show that the decrease of the cross-sectional average ion concentration along the flow direction within the particle stream [Formula: see text] is described by the diffusion length during the residence time with a characteristic velocity scale. In addition, the deformation of the particle stream due to inertial effects is described by a scaled Reynolds number that is a function of the flow rate ratio. The simulated particle stream thicknesses are validated by theory and a simple experiment. This paper reveals the relationship between the ion and particle concentrations and the dimensionless parameters for hydrodynamic focusing in the Y-shaped square microchannel under typical conditions.
对Y形方形微通道中流体动力聚焦下的三维离子和颗粒浓度进行了数值模拟，以阐明聚焦颗粒流中离子浓度沿流动方向的降低情况。该模拟模型在理论上由层流和平流扩散方程控制。控制方程采用有限体积法求解。在30种情况下，分析了分支通道汇合后五个横截面处的离子和颗粒浓度分布，其中鞘层与样品流速比Q/Q和雷诺数Re作为参数变化。结果表明，颗粒流中沿流动方向的横截面平均离子浓度降低[公式：见正文]由具有特征速度尺度的停留时间内的扩散长度描述。此外，颗粒流由于惯性效应的变形由作为流速比函数的标度雷诺数描述。模拟的颗粒流厚度通过理论和一个简单实验进行了验证。本文揭示了典型条件下Y形方形微通道中离子和颗粒浓度与流体动力聚焦的无量纲参数之间的关系。
