纳米流体分散稳定性的分子动力学研究初探

Elementary Research on the Dispersion and Stability of Nanofluids by Molecular Dynamics Simulations

纳米流体的制备和分散稳定性是纳米流体研究工作的前提。本文利用平衡分子动力学模拟方法,尝试从微观角度研究纳米流体的分散稳定性。以纳米颗粒Cu在液态CO_2中的分散稳定为算例,通过跟踪每个固体分子和液体分子的位置,分别观察了颗粒周围的液体吸附现象和颗粒的团聚现象。通过改变固液分子间的引力和斥力,观察其对颗粒周围液体分子的密度分布和颗粒团聚的影响。模拟结果显示,颗粒周围存在液体吸附层;增加固液间的引力,可以提高颗粒周围吸附液体分子的数目,但不改变液体层厚度;固液间引力的增强还可以有效抑制或延迟团聚的发生。这为纳米颗粒的分散稳定提供了新的思路。

The preparation and dispersionstability of nanofluids are basic work for follow-up research.In this paper,equilibrium molecular dynamics is used to investigate the dispersionstability of nanofluids with solid copper nanoparticles dispersed into the fluid CO_2.By tracking the position of the solid and fluid molecule,the fluid layer around the nanoparticle and nanoparticle aggregation are both investigated.They are also investigated by changing the attractive force and the repulsive force between solid and fluid molecule.The results show that a layer of fluid is formed around nanoparticle. More fluid molecules are attracted to form the layer around the nanoparticle when the attractive force between solid and fluid is increased,but the thickness of the fluid layer does not change.Nanoparticle aggregation is also controlled or delayed when the attractive force between solid and fluid is increased, which provides a new train of thought for nanoparticles dispersing into the fluid.