压-电场耦合下纳米尺度水输运的MD模拟

MD simulation of nanoscale water flow under coupled pressure-electric fields

运用分子动力学方法构建了纳米尺度的输运模型,针对纳米通道内水分子的流动与传热特性,分析了通道内压-电场耦合下水的速度分布、密度分布、自扩散系数和黏度等流动特性,同时也讨论了温度对通道内热导率的影响.模拟结果表明,速度轮廓从单纯电场驱动的电渗流型开始转变,由于压力的影响,速度分布呈抛物线型,速度随温度的升高而增大;温度的增加使分子有序度降低,水分子的笼状结构被逐渐破坏;随着温度的升高,热导率总体呈增大趋势;扩散系数随温度的升高从3.056 2×10-9 m2/s增大到2.483 6×10-8 m2/s;黏度也从0.131 320 mPa.s增大到0.139 748 mPa.s.

The nanoscale transport system is modeled by molecular dynamics（MD） simulation.The characteristics of water flow under coupled pressure-electric fields in nanochannel are studied with molecular dynamics.The influence of temperature on transport characteristics is also discussed.The nanofluidic properties,such as velocity profile,density,diffusion coefficient,viscosity and thermal conductivity are all obtained on the basis of thermo-physics statistical methods.The results show that,the velocity profile under coupled pressure-electric fields is no longer slug flow,but parabolic flow.The higher temperature causes the lower degree of order in water.With the increasing temperature,the heat transfer coefficient increases,the diffusion coefficient increases from 3.056 2×10-9 m2/s to 2.483 6×10-8 m2/s,and the viscosity also increases from 0.131 320 mPa·s to 0.139 748 mPa·s.