Experimental and theoretical scaling laws for transverse diffusive broadening in two-phase laminar flows in microchannels
Experimental and theoretical scaling laws for transverse diffusive broadening in two-phase laminar flows in microchannels
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DOI：
10.1063/1.126351
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发表时间：
2000-04-24
影响因子：
4
通讯作者：
Stone, HA
中科院分区：
文献类型：
--
作者：
Ismagilov, RF;Stroock, AD;Stone, HA
这封信从实验和理论上量化了低分子量物质在高佩克莱特数微通道中压力驱动层流中穿过两种水溶液之间界面的扩散。使用共焦荧光显微镜观察两种溶液分别携带的化学物质之间反应形成的荧光产物。在稳定状态下，邻近通道壁且横向于流动方向的界面处的反应扩散区的宽度按通道向下的轴向距离（从两股流的交汇点开始）和流动的平均速度的三分之一次方缩放，而不是在通道中间测量的更常见的二分之一次方缩放。如这封信中所述，需要对通道壁附近的反应扩散过程进行定量描述，以合理使用层流在微通道内进行空间分辨的表面化学和生物学，并了解表面附近剪切流中质量传递的三维特征。 (C) 2000 年美国物理研究所。 [S0003-6951(00)02616-4]。
This letter quantifies both experimentally and theoretically the diffusion of low-molecular-weight species across the interface between two aqueous solutions in pressure-driven laminar flow in microchannels at high Peclet numbers. Confocal fluorescent microscopy was used to visualize a fluorescent product formed by reaction between chemical species carried separately by the two solutions. At steady state, the width of the reaction-diffusion zone at the interface adjacent to the wall of the channel and transverse to the direction of flow scales as the one-third power of both the axial distance down the channel (from the point where the two streams join) and the average velocity of the flow, instead of the more familiar one-half power scaling which was measured in the middle of the channel. A quantitative description of reaction-diffusion processes near the walls of the channel, such as described in this letter, is required for the rational use of laminar flows for performing spatially resolved surface chemistry and biology inside microchannels and for understanding three-dimensional features of mass transport in shearing flows near surfaces. (C) 2000 American Institute of Physics. [S0003-6951(00)02616-4].