本文研究二階流體(Second-Grade Fluid)與福格特流體(Voigt fluid)在微尺度中的單向非穩態流動，流體稀薄化(rarefaction)產生的壁面滑移效應對於微間隙平板和微管內非穩態流動(unsteady)的影響。也對非微尺度的二階流體與福格特磁流體(MHD flow of Voigt fluids)的非穩態單向流，推導出在磁場的作用下，流經兩平行面時，流速分布和壓力梯度的變動情況。
文中分別分析如何應用壓力變化控制體積流率之方法，並研究六種實例： (1)梯形活塞運動(trapezoidal piston motion)；(2)等加速度(constant acceleration)；(3)突然被啟動之流動(impulsively started flow)；(4)突然被堵住之完全發展流動(impulsively blocked fully developed flow)；(5)振動流動(oscillatory flow)；(6)線性加速活塞運動(linear acceleration piston motion)。並藉由拉普拉斯轉換方法(Laplace transform technique)，由管內流非穩態動量方程式推導出速度(velocity)與壓力梯度(pressure gradient)關係的解析解。
分析過程我們針對活塞運動，以"肯德森數" (Knudsen number) Kn代表流體稀薄化程度，所得結果以圖形表示，並與流體無滑動邊界之結果相比較。得到以下結果，對於不同體積流率下的實例，當稀薄化效應越大，管壁的滑動現象越明顯，相對地使邊界速度也增加，在管內的速度反而減小；稀薄化效應對壓力梯度值的影響，在不同的實例中則有不同的變化。

The rarefaction effect of wall-slip conditions associated with unsteady unidirectional flows of second-grade fluid and Voigt fluids passing through a microtube or parallel microgap plates are studied in this study. The velocity profile and pressure gradient of an unsteady unidirectional flows of second-grade fluids and MHD Voigt fluids moving between two parallel surfaces under magnetic field effect are solved subsequently by the Laplace transform method.
The relationship between the change of volume flow rate and the pressure variations is analyzed for six different cases including：(1) trapezoidal piston motion, (2) constant acceleration, (3) impulsively started flow, (4) impulsively blocked fully-developed flow, (5) oscillatory flow, and (6) linear acceleration piston motion. The analytical solution of the velocity and pressure gradient for the momentum equations of unsteady flow in microtube are solved by using the Laplace transform technique.
In the analysis process, we focus on the trapezoidal piston motion. The Knudsen number( Kn) is used to represent the level of rarefaction. The results are presented graphically and compared to those of the continuum under no-slip condition. From the results, we found that, the effects of wall-slip becomes significant with the increase of rarefaction. The boundary velocity also increases as the velocity of the tube decreases with the same condition. The influence of flow rarefaction on the pressure gradient is varied quite a lot for different cases.

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