摘要
采用分子动力学方法模拟研究了不同压力下小分子气体在液压油中的扩散。模拟过程中均选用PCFF力场,首先对模拟体系进行NPT下500ps时间的动力学优化,随之进行NPT下500ps时间动力学模拟,得到其运动轨迹,并由爱因斯坦方程得出气体小分子在液压油中的扩散系数。该文还应用自由体积理论探究了小分子气体在液压油中的扩散机理,发现气体在液压油中以空穴形式存在的自由体积间进行扩散,即气体的扩散是通过先在一个空穴内不停振动,然后跳跃到下一个空穴来完成的。结果表明,随着压力的增大,小分子气体在液压油中的扩散系数是减小的。
The paper studies on the effects of pressure on gas diffusion in hydraulic oil by molecular dynamics simulation. The whole simulations were processed under PCFF force field. Refined the simulation system by NPT ensemble in 500 ps firstly, the diffusion coefficients were determined by NPT ensemble simulation in 500 ps.thencalculatedit from the Einstein relation. The small gas diffusion mechanism in hydraulic oil is also discussed according to free volume theory. Small gas molecules firstly oscillate inside one cavity of hydraulic oil and then jump from this cavity to another one to achieve the diffusion process. The results showed that the diffusion coefficient decreases with the rising pressure.
出处
《液压气动与密封》
2015年第9期16-19,共4页
Hydraulics Pneumatics & Seals
基金
上海市教委重点学科资助项目(J50603)
上海海事大学"学术新人"基金(YXR2014018)
关键词
压力
液压油
扩散系数
自由体积
分子动力学
pressure
hydraulic oil
diffusion coefficient
free volume
molecular dynamic
