Prabha Sooraj K, Sathian Sarith P
Computational Nanotechnology Laboratory, National Institute of Technology Calicut, Kozhikode-673 601, Kerala, India.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Apr;85(4 Pt 1):041201. doi: 10.1103/PhysRevE.85.041201. Epub 2012 Apr 16.
We report a molecular-dynamics study of flow of Lennard-Jones fluid through a nanochannel where size effects predominate. The momentum and energy accommodation coefficients, which determine the amount of slip and temperature jumps, are calculated for a three-dimensional Poiseuille flow through a nano-sized channel. Accommodation coefficients are calculated by considering a " gravity"- (acceleration field) driven Poiseuille flow between two infinite parallel walls that are maintained at a fixed temperature. The Knudsen number (Kn) dependency of the accommodation coefficients, slip length, and velocity profiles is investigated. The system is also studied by varying the strength of gravity. The accommodation coefficients are found to approach a limiting value with an increase in gravity and Kn. For low values of Kn (<0.15), the slip length obtained from the velocity profiles is found to match closely the results obtained from the linear slip model. Using the calculated values of accommodation coefficients, the first- and second-order slip models are validated in the early transition regime. The study demonstrates the applicability of the Navier-Stokes equation with the second-order slip model in the early transition regime.
我们报告了一项关于 Lennard-Jones 流体在尺寸效应占主导的纳米通道中流动的分子动力学研究。针对通过纳米尺寸通道的三维泊肃叶流，计算了决定滑移量和温度跳跃量的动量和能量适应系数。适应系数是通过考虑在保持固定温度的两个无限平行壁之间由“重力”（加速度场）驱动的泊肃叶流来计算的。研究了适应系数、滑移长度和速度分布对克努森数（Kn）的依赖性。还通过改变重力强度对该系统进行了研究。发现适应系数随着重力和 Kn 的增加而趋近于一个极限值。对于低 Kn 值（<0.15），从速度分布获得的滑移长度与从线性滑移模型获得的结果紧密匹配。利用计算得到的适应系数值，在早期过渡区域对一阶和二阶滑移模型进行了验证。该研究证明了纳维 - 斯托克斯方程与二阶滑移模型在早期过渡区域的适用性。
