LAUSR

Abstract The development of theoretical models for the estimation of physical properties of nanofluids such as viscosity is currently of a great deal of attention. In this regard, the present contribution aims to develop the friction theory for the correlation of nanofluid viscosity data. To do so, the Peng-Robinson and Esmaeilzadeh-Roshanfekr equations of state are applied to incorporate the repulsion and attraction pressure terms in the residual viscosity term of the friction model. 711 experimental data points of various nanofluids including water, methanol, and ethylene glycol as base fluids and Al2O3, SiO2, TiO2, and ZnO as nanoparticles were collected. The average absolute relative deviations of the collected data for 18 nanofluids are 2.38 and 2.46% for the Peng-Robinson and Esmaeilzadeh-Roshanfekr equations of state, respectively, and the R-squared values are 0.9978 and 0.9979 for the Peng-Robinson and Esmaeilzadeh-Roshanfekr equations of state, respectively, indicating very good performance of the developed model. The highest average absolute relative deviations were found to be 8.09% and 6.18% for water+TiO2 and water+ZnO nanofluids, respectively. However, the average error of viscosity calculations for almost all the cases is 16%.