矩形微流道内电渗流影响因素的数值模拟

针对电渗泵的设计参数优化问题,建立电渗驱动流的数学模型,应用有限控制容积法对矩形流道断面上双电层场和速度场的耦合控制方程进行数值求解.详尽分析流道断面深宽比、流道当量直径、电解质溶液浓度和外加电场强度对电势、速度和流量的影响,并给出电渗流量和平均速度与影响因素之间的拟合公式.仿真结果表明:流量随流道深宽比的增大而减小,当流道深宽比为1时,流量最小;流量随流道当量直径的平方增加;平均速度与电解质溶液浓度和外加电场强度有关、与流道深宽比和当量直径的大小基本无关.

NUMERICAL SIMULATION ON INFLUENCE FACTORS OF ELECTROOSMOTIC FLOW IN RECTANGULAR MICROCHANNEL

Aiming at the design parameter optimization prob- lem of the electroosmotic pumping,the mathematic model of electroosmotic flow is made.The coupling equations governing the electric double layer (EDL) field and the velocity field in the cross-section of rectangular microchannels are numerically solved by employing a finite control volume scheme.The de- pendence of the potential,velocity and volumetric flowrate on the aspect ratio,hydraulic diameter,liquid properties and the applied electrical field is analyzed.And the fitting polynomials of the relationships between the volumetric flow,average ve- locity and influence factors are presented.The numerical simu- lation results show that the volumetric flowrate decreases as the aspect ratio increases.When the aspect ratio approaches 1,the volumetric flowrate is minimum.The volumetric flowrate in- creased with the square of hydraulic diameter.The average velocity is dependent on the ionic concentration and the applied electrical field strength.However,the aspect ratio and hydraulic diameter have little impact on the average velocity.