微扩散管内幂律流体在不同外电场驱动下非稳态流动数值仿真

发布时间：2018-04-13 22:29

本文选题：微扩散管道 + 电渗流　；参考：《固体力学学报》2016年S1期

【摘要】：电场驱动下的非牛顿流体在微米级扩散管道内非稳态电渗流动特性是MEMS管设计人员关注的焦点,大部分实际液体可近似为用幂律模型描述的纯粘性流体,所以论文针对幂律流体在有限长微扩散管道内在两种不同形式的外加电场驱动下的非稳态电渗流动情况进行数值仿真.基于Ostwald-De Wael幂律模型和连续介质假说,采用高精度紧致有限差分离散二维完全Poisson-Boltzmann电势方程和Cauchy动量方程,对恒定电场及满足Maxwell方程的电场进行数值仿真,讨论了微扩散管中幂律流体在两种不同外加电场驱动下的瞬时流场分布的差异.结果表明,初始时刻固定扩散角和无量纲壁面电势,无量纲电动宽度的变化对幂律流体电渗流速度分布影响较大;在微扩散管上游等截面处,由恒定电场驱动及Maxwell电场驱动电渗流速度分布差别极小,在扩散管中下游则出现了明显的差别;由恒定电场驱动下的电渗流动在扩散管不同截面下的速度峰值相近,但Maxwell电场诱导的电渗流速度峰值则随管道半径变化出现较大差别.对于外加电场驱动的电渗流动,不同形式的外电场可使流场产生较大差别,而不同性质的流体也会形成不同的流场分布.
[Abstract]:The unsteady electroosmotic flow characteristics of non-Newtonian fluid driven by an electric field in a micron diffusion pipeline are the focus of attention of MEMS tube designers. Most of the actual fluids can be described as pure viscous fluid by power law model.In this paper, the unsteady electroosmotic flow of power law fluid under two different forms of external electric field in a finite-length micro-diffusion pipeline is numerically simulated.Based on the Ostwald-De Wael power law model and the continuum hypothesis, the steady electric field and the electric field satisfying the Maxwell equation are numerically simulated by using the high precision compact finite difference discrete two-dimensional complete Poisson-Boltzmann potential equation and Cauchy momentum equation.The difference of instantaneous flow field distribution of power law fluid driven by two different external electric fields in microdiffusion tube is discussed.The results show that at the initial moment, the changes of fixed diffusion angle, dimensionless wall potential and dimensionless electromotive width have a great influence on the electroosmotic velocity distribution of power-law fluid, and at the equal section of the upstream of the micro-diffusion tube,The velocity distribution of electroosmotic flow driven by constant electric field and Maxwell electric field is very small, but there is obvious difference in the middle and lower reaches of diffusion tube, and the peak value of electroosmotic flow driven by constant electric field at different sections of diffusion tube is similar.However, the peak value of electroosmotic velocity induced by Maxwell electric field varies greatly with the variation of pipeline radius.For the electroosmotic flow driven by an external electric field, different forms of external electric field can make a great difference in the flow field, and different properties of the fluid will form different flow field distribution.
【作者单位】：华中科技大学力学系;
【基金】：国家自然科学基金项目(11502087)资助
【分类号】：O357.3

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