负压强机制的格子玻尔兹曼方法研究  

Lattice Boltzmann method study for the mechanism of negative pressure

作　　者：封哲 李晋斌[1] 

机构地区：[1]南京航空航天大学理学院,江苏南京211106 [2]南京航空航天大学航天学院,江苏南京211106

出　　处：《大学物理》2014年第3期55-60,共6页College Physics

基　　金：国家自然科学基金(11104143);大学生创新训练计划项目(201310287185)资助

摘　　要：采用格子玻尔兹曼方法(LBM)研究了气液相变动态演化过程,并揭示气液混合体系中负压强的产生机理.本文采用多相流模拟中的单-陈模型(Shan-Chen模型)研究相变问题,该模型通过一个伪势来表示不同相之间的相互作用,从而控制不同相的分离,结合粒子间的相互作用力可得到一个能够描述非理想气体的状态方程,通过研究此状态方程,确定了发生相变和产生负压强的临界条件.再结合LBM,对相变和负压强现象进行数值模拟,并在气液混合体系中对拉普拉斯定律进行了验证.从模拟结果中发现,当液滴与周围气体处于力平衡和热平衡时,液滴内外压强差与其半径之间的关系满足拉普拉斯定律;另外,在气液交界面处会产生负压强,为使得理论解释与数值模拟结果相符,对于此处负压强的起源问题,我们采用同样能够描述非理想气体的范德瓦尔斯方程结合分子动力学的方法,导出内压强的变化会导致负压强的出现,并通过解释内压强的产生原因,从而进一步了解了负压强产生的微观机制.We use the lattice Boltzmann method （LBM） to study the evolution of phase transition procedure, and reveal the mechanism of negative pressure in the gas-liquid mixing system. Shan-Chen model can be used to simulate the phase transition phenomenon, this model uses a pseudo-potential to represent the interaction between different phases, thereby controlling the separation of different phases, with the help of inter-particle force we can obtain an equation of state like the van der Waals equation of state, then we can determine the critical conditions of phase transition and the generation of negative pressure through the study of the state equation. Using the LBM, it is possible to make the numerical simulation of phase transition and the negative pressure phenomenon, and verifying Laplace＇s law in the gas-liquid mixing system. From the results, we have found that when the droplet is in both force and thermal equilibrium with the surrounding gas, the relationship between the pressure difference and the droplet＇ s radius fits Laplace＇ s law very well. In addition, it generates negative pressure in the gas-liquid interface. To make the theoretical explanation consistent with the results of numerical simulation, we adopt the real van der Waals equation of state and the molecular dynamic method to explain the origin of negative pressure. When the inner pressure is strong enough, the negative pressure will appear. Explaining the generation of inner pressure causes further understanding of the microscopic mechanism of negative pressure.

关 键 词：格子玻尔兹曼方法 相变 负压强 拉普拉斯定律 内压强 

分 类 号：O359.1[理学—流体力学]