颗粒表面吸附层对纳米流体导热系数贡献的分子动力学研究

Molecular Dynamics Study of Contribution of the Particle Surface Absorption Layer to the Thermal Conductivity of Nanofluids

本文采用平衡分子动力学方法研究了纳米流体中固体颗粒周围的吸附层厚度及结构,并通过Green-Kubo原理计算了吸附层内导热系数的分布。研究表明,纳米颗粒周围存在0.5 nm厚的吸附层,层内原子数密度提高了50%~60%,导热系数提高了200%~300%。分析发现,吸附层导热系数的提高是由于原子数密度及吸附层内原子排列有序程度的提高引起的。该研究结果有望为建立合理的预测纳米流体的导热系数模型提供关键参数及理论指导。

In this article we studied the thickness and structure of absorption layer around nanoparticle and derived the thermal conductivity distribution based on the principle of Green-Kubo by equilibrium molecular dynamics simulation.The results showed that there is a 0.5-nm-thickness absorption layer with 50%-60%enhancement on atom number density and 200%-300%enhancement on thermal conductivity.It was found after analysis that the enhancement of thermal conductivity（TCE） is the result of both the enhancement of number density and the more ordered alignment of atoms within the absorption layer.Our work is expected to provide critical parameters for the establishment of the mathematical model for prediction of the thermal conductivity of various nanofluids.