纳米尺度孔隙内气体导热系数的分子动力学模拟

应用Lennard-Jone作用势,在300K和0.1MPa条件下,对边长20nm的立方体孔隙内氮气的导热系数进行了平衡分子动力学模拟. 结果得出分子分速度和速率的分布与统计力学得到的Maxwell速度和速率分布曲线基本一致,并且分子的平均自由程受到孔隙壁的严格限制. 通过Green-Kubo关系式计算得出了孔隙内氮气的导热系数,并与文献中的结果进行了比较,模拟结果接近于实验值,仅为同样条件下自由空间氮气的导热系数的1/3左右.

Molecular dynamics simulation of thermal conductivity of a gas in nanoscale pores

Using Lennard-Jones pair potential, the thermal conductivity of nitrogen in a cubic pore of 20?nm in length was calculated by equilibrium molecular dynamics (MD) simulation at 300?K and 0.1?MPa. The distributions of velocity component and speed of molecules calculated by the simulation and the Maxwell distribution equation fit very well. The mean free path of the molecules was strictly confined by the wall size of the nanoscale pore. The thermal conductivity of nitrogen in the nanoscale pore was determined by the Green-Kubo method and separately compared with the experimental and theoretic data in the literatures. The simulation result is close to the experimental one and only about one third of the value in the free space under the same conductions.