具有粗糙壁面微管道内非牛顿流体的电渗/电磁流动

Microfluidics means the fluid flow in a microchannel. It has many applications in physics, biology, medicine and chemistry. microfluidic devices are usually used to analyze biofluids, which are often solutions of long chain molecules which impart a non-Newtonian rheological behaviour. Many researchers have studied the electro-osmotic flows of non-Newtonian fluids in microchannel by imposed electrical field. However, with the increase of the strength of electrical field, the Joule heat effect becomes more obvious. In order to minimize the Joule heating effects, magnetic fields have been widely used to actuate the flow of microfluid. However, many theoretical works regarding to the influence of externally imposed magnetic fields need to be carried out in different micro-capillaries geometric domains. In fact, there are many roughnesses on surfaces of real channel walls, which are either incurred during the fabrication process or due to the adsorption of other species such as macromolecules. There small disturbances will affect the entire flow by penetrating itself into mainstream flow. The aim of the present study is to provide detailed analytical or numerical solutions both for EOF and magnetohydrodynamic velocity distributions of non-Newtonian fluids in a microchannel taking the wall roughness effects into account. Moreover, we will investigate the above flow under the case of rough curved microchannel. The dependence of velocity fields on several nondimensional parameters will be determined. The effect mechanism of corrugated walls on the EOF and magnetohydrodynamic flows will be revealed.

微流体力学是指微尺度管道内流体的流动问题，近年来它在物理、生物、医学和化学等多学科领域有着广泛的应用。微流体装置常被用来分析生物流体，这些流体大多是长链分子溶液，呈现出非牛顿流体的性质。用外加电场来驱动微管道中非牛顿流体的电渗流动已有部分学者在研究，但随着电场强度增加，将会产生较强的焦耳热效应。为了克服这一负面效应，最近人们提出通过外加磁场来研究微流体的输运过程，但此项技术的理论基础还很缺乏。同时，微流体管道在生产或操作过程中某些粒子会吸附到壁面上，不可避免地也会产生管道壁面粗糙度，它引起的微小扰动会渗入主流区而影响整个流动。本项目将通过理论分析和数值模拟，研究具有粗糙度微管道内非牛顿流体的电渗流动及电磁驱动流动，同时对具有粗糙壁面弯曲管道的情况进行研究。给出流场随相关参数的变化规律，揭示壁面粗糙度对电渗/电磁流动的影响机理。

微流体力学是指微尺度管道内流体的流动问题，近年来它在物理、生物、医学和化学等多学科领域有着广泛的应用。微流体装置常被用来分析生物流体，这些流体大多是长链分子溶液，呈现出非牛顿流体的性质。用外加电场来驱动微管道中非牛顿流体的电渗流动已有部分学者在研究，但随着电场强度增加，将会产生较强的焦耳热效应。为了克服这一负面效应，最近人们提出通过外加磁场来研究微流体的输运过程，但此项技术的理论基础还很缺乏。同时，微流体管道在生产或操作过程中某些粒子会吸附到壁面上，不可避免地也会产生管道壁面粗糙度，它引起的微小扰动会渗入主流区而影响整个流动。基于此，本项目首先开展了带有粗糙壁面的圆形和环形周期振荡的压力驱动下不可压缩粘性流体的流动研究，研究了无量纲的雷诺数、压力梯度振幅参数、壁面正弦粗糙度小振幅参数和反应粗糙度的正弦波波数对速度和体积流率的影响，另外，还研究了光滑壁面微管道中牛顿流体的旋转电渗流动（包括高电势的情况）。在此基础上，主要致力于研究带有壁面粗糙度的牛顿/非牛顿流体的电渗/电磁流动，分别研究了光滑壁面下非牛顿流体的电磁流动；带有壁面粗糙度的牛顿流体的电渗/电磁流动；带有壁面粗糙度的非牛顿流体的电渗/电磁流动，得到了相关的无量纲参数对流体运动的影响，分析了多场的耦合机理和规律。同时，还研究了非牛顿流体在微纳管道中电动流动。