耗散粒子动力学和纳维边界条件在微米纳米流体力学模拟中的应用

耗散粒子动力学是一种粗粒化的计算模拟方法,在微米和纳米流体力学中有着广泛的应用.由于界面在微小体积流体中的重要性,边界条件的选取在微米和纳米流体的研究中起到了关键性的作用.我们简单地介绍了耗散粒子动力学的模拟方法,并以此为基础,介绍了能够实现纳维边界条件的可调滑移长度的边界条件模拟方法.通过条纹状图案修饰的超疏水表面的流体力学行为研究,和高分子链在微米纳米流体器件中的运动研究2个例子,耗散粒子动力学结合纳维边界条件的模拟方法的实用性和可靠性得到了证实.     

Capillary filling in closed-end nanotubes

Capillary filling in small length scale is an important process in nanotechnology and microfabrication. When one end of the tube or channel is sealed, it is important to consider the escape of the trapped gas. We develop a dynamic model on capillary filling in closed-end tubes, based on the diffusion–convection equation and Henry's law of gas dissolution. We systematically investigate the filling dynamics for various sets of parameters, and compare the results with a previous model which assumes a linear density profile of dissolved gas and neglect the convective term.     

嵌段共聚物：物理与化学、生物和工程的美丽邂逅

基于过去三十年的不断探索,嵌段共聚物已成为研究分子自组装和相关基本现象的理想模型体系。定量化理论预测和精确实验观察的携手,使得对于嵌段共聚物平衡态相行为的理解已达成一致,并对于从分子组成到介观相结构,再到宏观材料性质的关联与机理有了比较完整的理解。文章回顾目前理解嵌段共聚物相行为的物理模型及其基本假设,并对嵌段共聚物在物理、化学、生物、工程等学科的研究进行展望。     

Thin film dynamics in coating problems using Onsager principle

A new variational method is proposed to investigate the dynamics of the thin film in a coating flow where a liquid is delivered through a fixed slot gap onto a moving substrate. A simplified ODE system has also been derived for the evolution of the thin film whose thickness h_f is asymptotically constant behind the coating front. We calculate the phase diagram as well as the film profiles and approximate the film thickness theoretically, and agreement with the well-known scaling law as Ca~(2/3) is found.