臺灣博碩士論文加值系統

本文以分子動力學(Molecular Dynamics)分法，研究L-J(12-6)液體在負壓下之均質成核行為與具溫度效應下之薄膜蒸發現象。均質成核部分採用固定平均壓力的方法對系統加熱直至接近飽和態液體線，經過一段時間後便出現成核現象。本研究所計算氣泡成長速率，與利用雷利方程式所求出的理論值相比約小一個數量級。此外，成核速率與氣泡成長速率會隨著負壓的增加而增加。本研究中氣泡約佔整體體積的50 到70%，此值接近巨觀中，以不會互相結合的球所形成之最密堆積所佔的比例(74%)。
液膜蒸發的研究，利用兩種模擬模式分別計算L-J(12-6)液體的蒸發係數與蒸發速率，並引入平均自由徑的觀念，藉此調整計算系統的體積。模擬的結果中發現液膜的溫度越高，則其介面(interface)厚度越厚。氬的蒸發係數隨溫度的增加而降低，其值約在0.162~0.098之間，分子脫離系統的速率約正比於計算模式所設定的脫離比例。

目 錄 頁碼
摘要 Ⅰ
致謝 Ⅱ
目錄 Ⅲ
圖目錄 Ⅵ
表目錄 Ⅸ
符號系統 Ⅹ
第一章 緒論 1
1.1 前言 1
1.2 研究背景與目的 2
1.3 論文結構 3
第二章 文獻回顧 4
2.1 分子動力學理論之文獻回顧 4
2.2 均質成核之文獻回顧 6
2.3 分子動力學應用於液膜蒸發之文獻 7
2.4 分子動力學應用於表面溫控之方法 8
第三章 分子動力學原理與計算方法 10
3.1 分子間的勢能模式 10
3.1.1 Lennard-Jones potential 10
3.1.2 自由分子與固體壁面分子間的勢能函數 12
3.1.3 固體分子間的勢能函數 13
3.2 週期性邊界條件 13
3.3 初始條件 14
3.3.1 初始位置 15
3.3.2 初始速度 16
3.3.3 質心速度歸零與溫度修正 18
3.4 最小映象法則 19
3.5 Verlet列表方法 21
3.6 無因次化計算 22
3.7 系統運動方程式 23
第四章 均質氣泡成核的模擬與分析 25
4.1 均質成核 25
4.1.1 系統模型 26
4.1.2 定壓曲線 27
4.1.3 均質成核模擬程式計算設定值 28
4.2 介穩態液體線 30
4.3系統壓力與溫度關係圖 32
4.4 氣泡成長圖譜 36
4.5 成核速率 43
4.6 氣泡成長速率 45
4.7 徑向分佈函數 51
第五章 液膜蒸發的模擬與分析 55
5.1 微液膜蒸發 55
5.1.1 系統模型 56
5.1.2 平均自由徑 58
5.1.3 液膜蒸發模擬程式計算設定值 59
5.2 密度分佈 60
5.3 溫度分佈 64
5.4 蒸發係數 69
5.5 蒸發速率 75
第六章 結論與建議 77
參考文獻 79

1T. Kinjo and M. Matsumoto, “Cavitation processes and negative pressure,” Fluid Phase Equilibria 144 (1-2), 343-350 (1998).
2T. Kinjo, K. Ohguchi, K. Yasuoka et al., “Computer simulation of fluid phase change: vapor nucleation and bubble formation dynamics,” Computational Materials Science 14 (1-4), 138-141 (1999).
3X. C. Zeng and D. W. Oxtoby, “Gas-liquid nucleation in Lennard- Jones fluids,” J. Chem. Phys. 94(6), 4472-4478 (1990).
4K. Yasuoka and M. Matsumoto, “Molecular simulation of evaporation and condensation I. Self condensation and molecular exchange,” ASME/JSME thermal Engineering Conference 2, 459-464 (1995).
5T. Tsuruta, H. Tanaka, T. Masuoka, “Condensation/evaporation coefficient and velocity distribution at liquid-vapor interface,” International Journal of Heat and Mass Transfer 42, 4107-4116 (1999).
6B. J. Alder and T. E. Wainwright, “Phase transition for a hard sphere system,” J. Chem. Phys. 27, 1208 (1957).
7A. Rahman, “Correlation in the motion of Atoms in Liquid argon,” Phys. Rev. 136, A405-A411 (1964).
8L. Verlet, “Computer “experiments” on classical fluids. I. Thermodynamical properties of Lennard-Jones molecules,” Phys. Rev. 159, 98-103 (1967).
9J. M. Haile, “Molecular Dynamics Simulation,” Wiley, New York, 332-339 (1992).
10Fan-Gang Tseng, Chang-Jin Kim, and Chin-Ming Ho, “A Monolithic, High Frequency Response, High-Resolution Microinjector array Ejecting Sub Pico-liter Droplets without Satellite Drops — Part I: Concepts, Designs and Molding,” paper submitted to Journal of Microelectromechanical System (2002).
11S. Park, J. G. Weng, and C. L. Tien, “Cavitation and bubble nucleation using molecular dynamics simulation,” Microscale Thermophysical Engineering 4 (3), 161-175 (2000).
12S. Maruyama and T. Kimura, “A molecular dynamics simulation of a bubble nucleation on solid surface,” Microscale Heat Transfer, Eurotherm Seminar #57, J. B. Saulnier, D. Lemonnier and J.-P. Bardon, Poitiers, 1998, pp. 175-182.
13F. van Swol, “Wetting at fluid- wall interface,” J. Chem. Soc. 82, 1685-1699 (1986).
14T. Tsuruta, G. Nagayama, “A molecular dynamics approach to interphase mass transfer between liquid and vapor,” Proceedings of the international conference on heat transfer and transport phenomena in microscale held at the Banff center conference, Banff, Canada,15-20 (2000).
15M. Chen, Z. Y. Guo, and X. G. Liang, “Molecular simulation of some thermophysical properties and phenomena,” Microscale Thermophysical Engineering 5 (1), 1-16 (2001).
16C. Tully, “Dynamics of gas-surface interactions: 3D generalized langevin model applied to fcc and bcc surface,” J. Chem. Phys. 73 (4), 1975-1985 (1980).
17J. Blömer, and A. E. Beylich, “Molecular dynamics simulation of energy accommodation of internal and translational degrees of freedom at gas-surface interfaces,” Surface science. 423, 127-133 (1999).
18S. Maruyama, “Molecular dynamics method for microscale heat transfer” Advances in numerical heat transfer. 2, 189-226 (2000).
19M. P. Allen and D. J. Tildesley, “Computer Simulation of Liquids,” Oxford, 21 (1987).
20潘欽 “沸騰熱傳與雙相流” 國立編譯館, 台灣, 12-16 (2001).
21J. J. Nicolas, K. E. Gubbins, W. B. Streett et al., “Equation of state for Lennard- Jones fluid,” Molecular Physics 37, 1429-1454 (1979).
22T. Kinjo and M. Matsumoto, “Cavitation processes and negative pressure,” Fluid Phase Equilibria 144 (1-2), 343-350 (1998).
23T. Kinjo, K. Ohguchi, K. Yasuoka et al., “Computer simulation of fluid phase change: vapor nucleation and bubble formation dynamics,” Computational Materials Science 14 (1-4), 138-141 (1999).
24T. E. Daubert, R. P. Danner, “Physical and thermodynamic properties of pure chemicals: data compilation,” Hemisphere Publishing Corporation, American (1983).
25G. A. Bird, “Molecular Gas Dynamics and the Direct Simulation of Gas Flows.” Oxford, 90-91 (1994).
26J. G. Collier and J. R. Thome, “Convective Boiling and Condensation .” Oxford, 433-438 (1994).