基于粗粒化水分子模型的Cu-H_2O纳米流体黏度模拟

SIMULATION STUDIES OF VISCOSITIES OF Cu-H_2O NANOFLUIDS BASED ON COARSE GRAINING WATER MOLECULES

分子动力学模拟是研究纳米流体的黏度特性的重要手段,但计算量庞大.文章通过对基液水分子粗粒化,使得计算量大幅度减小,且计算精度与全原子模拟相当.基于平衡态分子动力学,模拟研究了Cu-H2O纳米体系的微观运动特性,通过格林-库博(Green--Kubo)公式对Cu-H2O纳米流体的黏度进行了模拟计算,并考察了温度、体积分数、粒径和颗粒形状对于Cu-H2O纳米流体黏度的影响,对已有的悬浮液黏度经验公式进行了修正.

Molecular dynamics simulation is an important approach to study the viscosity characteristics of nanofluids but its computation scale is huge. In this paper, the computation scale is significantly reduced by applying the Martini force field on water-based fluid and coarse-graining water molecules. The micromotion of copper nanoclusters in water-based fluid was simulated based on the equilibrium molecular dynamics. The viscosities of Cu-H2O nanofluids were calculated through the Green-Kubo formula. The effects of fluid temperature, volume fraction, shape and size of the particles on the viscosities of Cu-H2O nanofluids were studied, based on which the existing empirical formula of the viscosity of suspension was modified.