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

Dissipative Particle Dynamics and Navier Boundary Condition Simulations in Micro-and Nanofluidics

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.

Dissipative particle dynamics （DPD） is an established method for mesoscale coarse-graining fluid simulations, and has a broad range of applications in studies of micro- and nanofluidics. The method is fully off- lattice and particle based and naturally includes thermal fluctuations. Due to the importance of surface interaction, the choice of boundary condition is essential to micro- and nanofluidic researches. No-slip boundary condition, where the fluid velocity vanishes at a fluid/solid interface, is widely accepted for macroscopic fluids. A more general boundary condition is the Navier boundary condition,which allows fluid to slip. Here we briefly reviewed the DPD method and the tunable-slip method that implements the Navier boundary condition. The applicability and reliability of the simulation methods are demonstrated using two examples：one is the study of flow over a superhydrophobic surface with striped pattern. The simulation results show good agreement with the theoretic and numerical predictions. The second example is the polymer dynamics in a mierofluidic device. The modification of the boundary condition can induce different polymer dynamics under confinement. Both examples demonstrate that DPD simulations can provide guidance in the design of better and efficient micro- and nanofluidic devices.