中文摘要：

采用分子动力学模拟方法，研究了不同表面电荷密度下圆柱形纳米管道中溶液粒子分布情况及电渗流特性．采用更为接近工程实际的纳米管道模型，在管道中段离散分布一定数目的单位元电荷，平衡后，再取出该段在两端加上电场进行电渗流驱动过程模拟．仿真结果表明，表面电荷密度越大，电荷倒置现象越明显，电荷倒置现象对电渗流有直接影响；其次，仿真结果也表明基于连续体理论的Poisson-Boltzman方程已不能准确地描述纳米管道中的离子分布情况，尤其是在靠近管壁附近，该方程得到的离子浓度与模拟结果差异较大；基于Navier-Stokes方程的流体动力学理论，对其边界条件作适当改变后，在管中心区域其预测结果可以与模拟结果吻合得较好；而在靠近管壁的区域由于溶液粘度发生变化，连续理论的预测与模拟结果存在明显差异．

英文摘要：

Ion distribution and the electroosmotic flow of the fluid confined in the cylindrical nanotubes with different surface-charge density are studied using molecular dynamics simulations. A more practical nanotube model was employed compared with the previous work. The nanotube was first partially charged in the middle region with different number of discrete elementary charges. When the system reaches equilibrium state, the middle region was extracted as the electroosmotic flow pump. The simulations were carried out with an extra voltage acted on the pump. Simulation results indicate that with higher surface-charge density, the phenomenon of charge inversion is more evident. The charge inversion directly influences the velocity profiles of the electroosmotic flow. The Poisson-Boltzman equation based on the continuum theories fails to describe the ionic distribution in the nanotubes exactly. Particularly, the predicted ionic distribution near the wall from the Poisson-Boltzman equation differed greatly from the MD simulation results. While given proper boundary conditions, the classic hydrodynamic theory based on the Navier-Stokes equation can predict the velocity profiles of the electroosmotic flow well in the center of the nanotubes, but diverges from the simulation results near the wall due to the sharp increase of the liquid viscosity.