近十年來微電子機械系統的加工與應用已有了巨大進展，已經能夠加工一些微裝置，如微型泵，微型閥，微感測器等，但由於尚缺乏充分理論的指導及支持，這些裝置的功能的並非全然理想，這促使人們反過來加強理論方面的研究。
　　微機電系統常常會牽涉到微奈米尺度的流場問題。傳統的方法已不能有效分析微觀尺度的傳輸現象。這個問題的發生主因在於微觀尺寸或高應力作用下連續體或平衡假設已不能成立。為了處理這類微觀尺度問題我們使用分子動力學模擬以幫助了解微觀傳輸機制，流體-結構相互作用和在微觀下的尺度效應。
　　本文採用分子動力學方法探討微系統中流場行為，採Lennard-Jones勢能函數模擬分子間勢能及作用力，流體分子以液態氬(Ar)模擬，固體分子則以銅分子(Cu)模擬，本文由兩種模型比較由固體及流體拖曳孔穴流之流場行為。模型一是長寬比為二比一的微孔穴模擬，以平板抽動當作驅動力。模型二則以壓力方式來驅動流體以拖動孔穴流，吾人著眼於暫態狀態之呈現並探討其速度、密度分布情形，並提出日後在於生醫及工程方面之可能應用。

　Recently, the applications of micro-fluidic devices or nano-fluidic devices in various fields (such as bio-chemical analysis, energy and biomedical engineering) have been greatly developed. Particularly, the fluid transports play a crucial role in these systems, for example, the bio-samples or regents are transported by the motion of fluid in the micro-bio-chemical analysis systems. However, the order of the characteristic length scales in these systems is micro or nano, the Knudsen number may be very large compared to macro-scale and hence the assumption of continuum breaking down here; in other words, the traditional Navier-Stokes equations and analysis approaches may not be applicable to describe the motion of fluid in these systems.
　Accordingly, this study adopts Molecular Dynamic (MD) simulation to investigate the motion of fluid in nano-scale channels. The interaction of liquid-liquid molecules, liquid-solid molecules and solid-solid molecules are all modeled by a simple “Lennard-Jones potential” theory. Here the liquid is composed of Argon (Ar) atoms and the solid is composed of copper (Cu) atoms. There are two main issues studied in this work: (1) cavity flows in nano-scale (the ratio of the length to the width of cavity is 2), (2) pressure-driven flows in a nano-channel with a cavity. The transient processes of the motion of fluid and the properties of fluid in the two issues are simulated and then discussed.
　Finally, we think the results of this work are useful to the applications of nano-devices in bio-chemical analysis, biomedical and energy engineering.

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