A Simple and Effective Boundary Model in Nonequilibrium Molecular Dynamics Method  

作　　者：Cui-liu Fu 孙昭艳 

机构地区：[1]State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China [2]Xinjiang Laboratory of Phase Transitions and Microstructures in Condensed Matters, College of Physical Science and Technology, Yili Normal University, Yining 835000, China

出　　处：《Chinese Journal of Polymer Science》2016年第9期1150-1157,共8页高分子科学（英文版）

基　　金：financially supported by the National Basic Research Program of China(973 Program,2012CB821500);supported by the National Natural Science Foundation of China(Nos.21222407,21104082 and 21474111)

摘　　要：Abstract We propose a simple and effective boundary model in a nonequilibrium molecular dynamics （NEMD） simulation to study the out-of-equilibrium dynamics of polymer fluids. The present boundary model can effectively weaken the depletion effect and the slip effect near the boundary, and remove the unwanted heat instantly. The validity of the boundary model is checked by investigating the flow behavior of dilute polymer solution driven by an external force. Reasonable density distributions of both polymer and solvent particles, velocity profiles of the solvent and temperature profiles of the system are obtained. Furthermore, the studied polymer chain shows a cross-streaming migration towards center of the tube, which is consistent with that predicted in previous literatures. These numerical results give powerful evidences for the validity of the present boundary model. Besides, the boundary model can also be used in other flows in addition to the Poiseuille flow.Abstract We propose a simple and effective boundary model in a nonequilibrium molecular dynamics （NEMD） simulation to study the out-of-equilibrium dynamics of polymer fluids. The present boundary model can effectively weaken the depletion effect and the slip effect near the boundary, and remove the unwanted heat instantly. The validity of the boundary model is checked by investigating the flow behavior of dilute polymer solution driven by an external force. Reasonable density distributions of both polymer and solvent particles, velocity profiles of the solvent and temperature profiles of the system are obtained. Furthermore, the studied polymer chain shows a cross-streaming migration towards center of the tube, which is consistent with that predicted in previous literatures. These numerical results give powerful evidences for the validity of the present boundary model. Besides, the boundary model can also be used in other flows in addition to the Poiseuille flow.

关 键 词：Boundary condition Depletion effect Velocity profile Density distribution Nonequilibrium moleculardynamics. 

分 类 号：O631.21[理学—高分子化学]