Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow.
Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow.
复制标题
电渗和压力驱动流相结合的微通道中跨流扩散的比例定律。
DOI：
10.1007/s10404-012-1058-8
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发表时间：
2013
影响因子：
2.8
通讯作者：
Pant,Kapil
中科院分区：
文献类型：
--
作者：
Song,Hongjun;Wang,Yi;Pant,Kapil
本文对电渗透流和压力驱动流联合作用下分析物在矩形微通道内的横向扩散进行了分析研究，探讨了分析物的非均质输运行为和空间依赖的扩散标度规律。基于薄双电层的假设，建立了一个能够准确描述任意宽高比微通道三维稳态对流扩散的解析模型。该模型在流速和分析物浓度剖面方面进行了高保真数值模拟验证，结果非常吻合（相对误差< 0.5%）。然后进行了广泛的参数分析，以询问组合流速场对正压梯度（PPG）和负压梯度情况下输运行为的影响。利用解析模型首次获得了PPG情况下从纺锤形浓度曲线，经过条形浓度曲线（纯EOF），最后到蝴蝶形浓度曲线的演化过程，并定量描述了在大范围参数空间内扩散层厚度和标度规律的空间依赖性。
This paper presents an analytical study of the cross-stream diffusion of an analyte in a rectangular microchannel under combined electroosmotic flow (EOF) and pressure driven flow to investigate the heterogeneous transport behavior and spatially dependent diffusion scaling law. An analytical model capable of accurately describing 3D steady-state convection–diffusion in microchannels with arbitrary aspect ratios is developed based on the assumption of the thin electric double layer. The model is verified against high-fidelity numerical simulation in terms of flow velocity and analyte concentration profiles with excellent agreement (<0.5 % relative error). An extensive parametric analysis is then undertaken to interrogate the effect of the combined flow velocity field on the transport behavior in both the positive pressure gradient (PPG) and negative pressure gradient cases. For the first time, the evolution from the spindle-shaped concentration profile in the PPG case, via the stripe-shaped profile (pure EOF), and finally to the butterfly shaped profile in the PPG case is obtained using the analytical model along with a quantitative depiction of the spatially dependent diffusion layer thickness and scaling law across a wide range of the parameter space.