垂向磁场作用下微通道内的电渗流动与传热研究

微流体流动是指在微尺度管道内流体的流动问题，近年来在物理、生物、医学和化学等多学科领域有着广泛的应用。通常电解质溶液中的离子与微管道壁面的相互作用会产生双电层(EDL)，在外电场的作用下，由于流体的粘性，移动的自由离子将会带动附近流体微团运动，最终形成了电渗流(EOF)。牛顿流体和非牛顿流体的EOF 在理论和实验中研究的较多，并已成为一项成熟的技术。但随着电场强度的增加，焦耳热效应的产生不可避免。为了减少焦耳热的负面效应，最近人们提出利用外加垂向磁场来增加粒子EOF 分离和混合的效率，但此项技术的理论基础还很缺乏。本项目将通过理论分析和数值模拟，研究外加垂向磁场作用下，壁面粗糙度和滑移边界条件对微管道牛顿和非牛顿流体的电渗流动和热传导特性。给出流场和温度场随相关参数的变化规律，揭示外加磁场对减小EOF焦耳热效应的影响机理。

Microfluidics means the fluid flow in a microchannel. It has many applications in physics, biology, medicine and chemistry. When an electrolyte comes in contact with a microchannel wall in which the fluid flows, it will result in the formation of an electric double layer (EDL). When an electric field is applied tangentially along the charged surface, the migration of the mobile ions will carry the adjacent and bulk liquid phase by viscosity, resulting in an electroosmotic flow (EOF).Now the EOF is widely used and becomes a mature technology due to the theoretical and experimental investigations. However, with the increase of strengthof electric field, the Joule heat effect will occur inevitably. In order to minimize the Joule heating effects in EOF, magnetic fields have been widely used. However,many theoretical works regarding to the influence of externally imposed magnetic fields on EOF need to be carried out in different micro-capillaries geometric domains. The aim of the present study is to provide detailed analytical or numerical solutions for magnetohydrodynamic velocity and temperature distributions of Newtonian and non-Newtonian fluids in a microchannel taking the wall roughness and slip conditions effects into account. The dependence of velocity and temperature fields on several nondimensional parameters will be determined. The acquired knowledge will build the mechanism for deducing the Joule heating effects of future microdevices.