Examining rheological behavior of MWCNT-TiO₂/5W40 hybrid nanofluid based on experiments and RSM/ANN modeling

In this study, the rheological behavior of MWCNT-TiO₂/5W40 hybrid nanofluid was examined experimentally and then the results were compared with regression-based methodologies. Performing FESEM and DLS, the molecular structure, nanoparticle size distribution of the samples were inspected. To examine the effect of nanoparticles, the viscosity of the base fluid and the nanofluid were measured and compared at 20–60 °C and 0.05–1 vol% using Brookfield viscometer. The results showed that 5 W40 and MWCNT-TiO₂/5W40 conform to Newtonian and non-Newtonian fluid classification. The nanofluid viscosity intensified with decreasing shear rate as well as temperature and increasing volume fraction. The presence of nanoparticles amplified the nanofluid viscosity up to 790%. In the numerical section, the neural network capability was challenged and it was observed that the maximum error was below 5% and considering of R² = 0.999, the viscosity ratio forecasting was acceptable.