突扩微通道中流体电渗驱动的LBM模拟研究  

LATTICE BOLTZMANN SIMULATION OF ELECTROOSMOTIC FLOWS IN MICROCHANNEL WITH A SUDDEN EXPANSION

作　　者：聂德明[1,2] 林建忠[1,2] 

机构地区：[1]浙江大学力学系,杭州310027 [2]中国计量学院计量测试工程学院,杭州310018

出　　处：《力学学报》2010年第5期838-847,共10页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金重点资助项目(10632070)~~

摘　　要：通过带有外力项的不可压格子Boltzmann方法模拟了突扩微通道中的电渗流动.深入研究了扩张比ER,离子摩尔浓度c。。,ζ电势及外加电压对流动的影响.计算结果表明,与压力驱动相比,在突扩通道中电渗驱动可以抑制边界层的分离.同时,流速、压力、壁面电荷电势在突扩处均发生突变,且这种突变与扩张比ER及离子摩尔浓度c。。紧密相关.外加电压沿通道轴线呈线性分布,但在突扩处存在拐点.而且,随着ER增大收缩通道中的压力由线性向非线性转变.研究还发现,随着ER或c_∞逐渐增大,通道出口速度剖面由凸形向凹形转变.这是由于扩张通道中的逆压力梯度与流体所受的电场力相互作用的结果.此外,在其他条件不变的情况下,ζ电势和外加电压对出口速度剖面没有影响.Great progress has been carried out on the Micro Total Analysis System（μTAS） in recent years, in which the chemical analysis system is miniaturized by micromachining.This system can reduce reagent consumption,dispersion effects and analysis time.Nowadays,μTAS devices are beginning to make significant contributions to biotechnology,biomedicine and drug discovery.Meanwhile,due to the difficulties of controlling fluid motion in such a small scale,fluid flow driven in microfluidic devices has received increasing attention.So far electroosmotic flow（EOF） is one of the most popular and important fluid driven techniques in microfluidic devices because in an EOF the velocity profile is plug-like and the mean velocity is independent of the cross-sectional area,as well as its valveless control of fluid flow.Therefore,electro-osmotic flow can offer significantly less deleterious dispersive effects than pressure-driven flow and provide a favored high-performance sample separation technique.Due to its importance,electroosmotic flow in microchannels has received considerable attentions recently and been investigated both numerically and experimentally. However,fluid flow in microfluidic devices is often through channels with changes in cross-sectional area, and/or channels with bends and bifurcations,which make a great difference to velocity profile,pressure distribution and so on.A systematic study of these different configurations will provide valuable insight into the flow physics.The goal of the present study is to undertake a numerical study of EOF in microchannels with a sudden expansion in order to identify the factors affecting the flow.The present work is in the use of an incompressible lattice-Boltzmann model with a forcing term which is perhaps better suited to microflows than the conventional Navier-Stokes solvers.The impact of expansion ratio（ER）,ionic molar concentration（c_∞）, external electric potential and zeta potential on the flows are investigated.Numerical results including velocity prof

关 键 词：微通道 突扩 电渗流 格子BOLTZMANN方法 数值模拟 

分 类 号：O357.1[理学—流体力学]