電流變流體之電滲流動解析

Analysis on Electroosmotic Flows of Electrorheological Fluids

陳子殷(Zih-Yin Chen)

指導教授 ： 黃信富

國立臺灣大學/工學院/機械工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201600972

摘要

電驅動流體力學因為近年來微流體科學的迅速發展而受到眾多微流體研究者的重視。其中，因為工作流體大多為非牛頓流體，為使電驅動微流體裝置在設計及操作上能夠準確，吾人認為對於微流道中非牛頓流體電滲流有正確的描述與了解是極為重要的。本研究主要的目的是探究微流道中非牛頓正電流變流體之電滲流動效應。吾人考慮旋轉黏滯係數，與電流變懸浮液流體中微粒的電極化向量及電力矩向量所帶來的效果，解出適用於多數流場情況的解析解，並改變解析解內不同的參數條件，以了解上述參數對於流體旋轉及線性運動流況的變化關係。本研究由羅森史威格(Rosensweig)的流體模型與統馭方程式出發，結合電流變懸浮液流體極化鬆弛的概念，描述微粒極化對於巨觀流場極化密度及體電力矩的關係。再者，吾人引入能斯特-普朗克方程式(Nernst-Planck equation)與泊松-波茲曼方程式(Poisson-Boltzmann equation) 來分析正電流變流體在微流道中的電滲流，並在適當的假設下，解出流場角速度與線速度之解析解。此外，本文亦考慮同時具有壓力梯度與電滲力之電流變流體電滲流，並藉由調整梅森數(Mason number)來了解正電流變流體電滲流的電流變效應。最後，藉由使正電流變流體電滲流流量歸零，來計算正電流變流體電滲流在微流道中的建壓(Pressure build-up)強度與壓力分佈。

關鍵字

微流道 ； 電滲流 ； 電流變流體 ； 旋轉黏滯係數 ； 電流變效應 ； 梅森數 ； 建壓

並列摘要

Due to the rapid development of microfluidics science in the past few decades, the fundamental physics and practical applications of electrically driven fluid flows are widely studied by researchers in the microfluidics field. However, most of the working fluids found in micro systems are non-Newtonian fluids. Therefore, an accurate understanding and description of non-Newtonian electroosmotic microchannel flows is most desirable and has practical significance in optimizing the design and operation of microfluidic devices. In this thesis, we aim to investigate and analyze electroosmotic flows of positive electrorheological fluids. By considering the effect of spin viscosity, electrical polarization, and electrical torque on the electrorheological suspension liquids, we derive general analytical solutions suitable for describing most of the flow conditions. By varying the relevant physical parameters in the analytical solutions, we examine how variations in these parameters may influence the electrorheological electroosmotic flow behavior and responses.
Based on the Rosensweig fluid modeling equations and introducing the concept of polarization relaxation of electrorheological liquids, we combine the physics of fluid electrical polarization, body torque input, and interfacial electrical double layers such that analytical solutions to the spin velocity and linear velocity fields of the electrorheological electroosmotic flows can be obtained. Lastly, we examine the influence of pressure gradients on the electrorheological electroosmotic flows by varying the Mason number, that is, a ratio between the hydrodynamic forces and the electrostatic forces. Finally, we present results on the pumping pressure to evaluate the pumping pressure build-up of the positive-electrorheological electroosmotic flows considered herein.

並列關鍵字

microchannel ； electroosmotic flow ； electrorheological fluid ； spin viscosity ； electrorheological effect ； Mason number ； pressure build-up

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