Experimental study of rheological behavior of MWCNT (50%)-MgO (50%)/SAE40 hybrid nanofluid: Dynamic viscosity optimization and numerical simulation of turbulent flow

Abstract

In the present report, the rheological behavior of MWCNT (50 %)-MgO (50 %)/SAE40 hybrid nanofluid (HNF) is investigated experimentally/statistically/numerically in different laboratory conditions. Viscosity is measured at temperatures of T = 25–50 °C, solid volume fraction of SVF = 0.0625–1 % and a shear rate of SR = 666.5–9331 s−1. The rheological behavior of the resulting HNF is fitted by the Ostwald–de Waele model. Mathematical calculations based on the power-law model and considering the dependence of viscosity on the SR, show that the HNF is a pseudo-plastic non-Newtonian fluid. The highest values ​​of increase and decrease of viscosity are equal to + 28.70 % (at T = 25 °C, SVF = 1 % and SR = 2666 s−1) and −5.91 % (at T = 25 °C, SVF = 0.0625 % and SR = 3999 s−1, respectively). Based on the response surface methodology (RSM), a mathematical model with a coefficient of determination of 0.9994 is presented to estimate laboratory data. Using a numerical simulation of flow in the branch pipe, the parameters of pressure drop, shear rate and flow velocity compared to the witness fluid flow increase by + 17.05 %, +18.43 %, and + 3.29 %, respectively.