Lennard-Jones流體在超重力場下的氣液相平衡

本研究運用分子動態模擬法分別模擬Lennard-Jones流體單原子分子、雙原子分子與三原子分子三種分子氣液共存系統，計算求得液相密度、氣相密度和界面張力，我們利用臨界指數關係式分析其結果，並求出三種系統的臨界溫度與臨界密度，分別為單原子分子Tc*=1.0854 ρc*=0.3133、雙原子分子Tc*=1.4450 ρc*=0.2906與三原子分子Tc*=1.6533ρc*=0.2719，進而我們檢查界面張力與溫度間的臨界指數關係，發現三種系統皆與理論值1.26相吻合。在模擬氣液兩相共存系統時，界面張力會受界面面積的影響。界面面積增大，界面張力會減小，但界面面積的影響只在面積很小時才發生。當系統受一超重力場作用時，系統液相密度增加，氣相密度減小，界面張力增大。

關鍵字

超重力場；氣液相平衡；分子模擬

並列摘要

Molecular dynamics simulations are used to study the phase equilibrium of the vapor-liquid coexistence system. In this study, we simulated Lennard-Jones fluid, two-center Lennard-Jones fluid and three-center Lennard-Jones fluid, and calculated the liquid density, the vapor density, and the surface tension. According to the scaling law, the critical temperature and critical density of these systems were determined. They are Tc*=1.0854 ρc*=0.3133 for the Lennard-Jones fluid, Tc*=1.4450 ρc*=0.2906 for the two-center Lennard-Jones fluid, and Tc*=1.6533ρc*=0.2719 for the three-center Lennard-Jones fluid. We checked the relationship between the surface tension and the temperature. The temperature dependence of the surface tension is well described by the scaling law. The effect of the surface area on the surface tension was investigated. It is found that the surface tension increases with the decrease in the surface area. However, this effect is pronounced only in small surface areas. When the vapor-liquid equilibrium system is under high gravity, the liquid density increases, the vapor density decreases, and the surface tension increases.

並列關鍵字

high gravity ； vapor-liquid equilibrium ； molecular simulation

參考文獻

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國際替代計量

Lennard-Jones流體在超重力場下的氣液相平衡

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