Numerical study of the effects of Brownian motion and interfacial layer on the viscosity of nanofluid (Au-H2O)

Until now, the contribution of nanoscale mechanisms to shear viscosity enhancement of nanofluid have only been postulated in experiments. This paper presents the study of equilibrium molecular dynamics simulation to explore the nanoscale mechanisms such as Brownian motion of gold nanoparticles and interfacial layer at water - gold interface, and to investigate their effects on the shear viscosity enhance-ment in nanofluid (Au-H2O). Moreover, the computationally efficient model of TIP4P/2005 model was used to model the water, and the shear viscosity has been calculated through the molecular dynamics coupled with Green-Kubo formula. In addition, this numerical study was performed in the temperature range of 288 K to 338 K and at different gold volume fractions of 2.6%, 3.2%, 4.0% and 5.2%. The results have revealed that the decreasing shear viscosity of nanofluid (Au-H2O) with increasing the temperature is due to an increase in the Brownian motion, and that the interfacial layer at water - gold interface con -tributes to shear viscosity enhancement of aqueous nanofluid containing the gold nanoparticles. Furthermore, the results have shown that the formation of a liquid layer at the pure water-gold interface is not affected by that the Brownian motion of gold nanoparticles in pure water.(c) 2021 Published by Elsevier B.V.