Rheological behavior of CuO/EG:W (20:80 v/v) nanofluid from a thermal perspective: Experimental study, development of new correlation, and sensitivity analysis

This study investigates the viscosity of CuO/EG:W (20:80 v/v) nanofluid in the solid volume fraction from 0 to 1% and temperatures between 15 and 50 degrees C. Examining the correlation between the shear stress and shear rate obtained from experiment test at different temperatures and solid volume fractions revealed that the investigated nanofluid behaves much very carefully like the Newtonian fluid behavior. Therefore, observing the independency of the viscosity to the shear rate was not unexpected in the results. During analyzing, the authors found that the viscosity of investigated nanofluid has a very low sensitivity to temperature changes but it is significantly influenced by changes in the solid volume fraction and nanoparticle concentration. In this research, a new experimental correlation was suggested to predict the viscosity of the investigated nanofluid in the expressed range of temperature and solid volume fraction to model the test results. In the mentioned correlation, the viscosity is expressed as the relative variable to independent variables (temperature and solid volume fraction). R-2 (R-squared) value for the expressed correlation was 0.9850, which shows the accuracy in the presented experimental correlation to predict the nanofluid viscosity in the concentration and the temperature range.