Experimental investigation of rheological behavior of fullerene/hydraulic oil nanofluid

In this study, the viscosity of the fullerene/hydraulic oil nanofluid has been investigated experimentally. The purpose of this research is improving the properties of hydraulic oil by adding fullerene nanoparticles at the volume fractions of 0.05% to 2% in the base fluid. Hence, the nanofluid has been prepared by a two-step method using an ultrasonic homogenizer. The results showed that nanofluid behavior is non-Newtonian in all volume fractions. Moreover, in accordance with other common fluids, the viscosity of the nanofluid declined with rising temperature. The changes of viscosity included two trends. The maximum value of the viscosity at each temperature occurred at concentration of 0.4%, and it decreased at higher concentrations. Furthermore, comparing experimental results with the presented models revealed that previous analytical models are not able to predict the viscosity of the fullerene/hydraulic oil nanofluid. Hence, the response surface methodology has been applied to predict the dynamic viscosity of the hydraulic oil containing fullerene nanoparticle.