分子动力学方法研究纳米尺度下液滴蒸发的物理规律

采用分子动力学方法对纳米尺度下氩液滴在氩蒸气中蒸发过程进行了模拟,其中液相分子采用球形截断的Lennard-Jones势能函数描述。模拟过程首先在三维模拟空间产生准稳态平衡的液滴和周围气相环境,随后控制液滴的外界物理条件形成蒸发现象,同步记录气液两相分子坐标和动量变化,从微观信息中统计计算出相应的宏观物理信息。研究了蒸发初始液滴半径的不同研究其对液滴蒸发过程的影响,结果表明纳米尺度下液滴蒸发现象与微米以上尺度液滴蒸发现象存在差异;引入等效辐射能的概念在分子动力学方法中实现了对辐射能传递过程的模拟,证实了辐射传递能量会对纳米尺度液滴蒸发过程产生很大的影响。

Molecular dynamics investigation on regular patterns of nano-droplet evaporation

Molecular dynamics method was used to study the evaporation process of a nano-scale argon droplet into its own vapor,in which spherical truncated Lennard-Jones function described the potential energy between two liquid phase molecules.Quasi equilibrium state of the droplet and the surrounding vapor were formed in a simulation space firstly,then the outside physical conditions of the external vapor and the droplet were changed therefore the droplet begins to evaporate.The coordinate and momentum of each molecule were recorded during the evaporation process,and some macroscopic physical parameters were calculated statistically.The influence of different initial droplet radius on droplet evaporation was studied,and the result proves that evaporation phenomena of the nano-scale droplet evaporation and ones of the macro-scale droplet evaporation are different.The concept of "equivalent radiation" was introduced into the molecular dynamics method for the simulation of radiant energy transfer process,and it is concluded that radiation heat transfer has an important impact on the evaporation of nanometer-size droplet.