Gholamreza Sholeh - Graduate Masters, Islamic Azad University Nour Branch, Mazandaran, Iran
Dariush Mansoury - Faculty member, College of Marine Science, Tarbiat Modarres University and lecturer in Islamic Azad University Nour Branch, Mazandaran, Iran

In the study of the physical properties of nanofluids, Viscosity is an important quantity. The importance of this physical properties due to its direct relation to the pressure drop and pumping power of nanofluids. Accordingly, keeping viscosity in minimum quantity have a special importance. many factors, affect the viscosity of nanofluids. In this study, the effect of polyvinylpyrrolidone surfactant on the viscosity of silver nanofluid has been investigated. Silver nanofluids were made at a concentration of 0.8 wt%. After the tests, the optimal concentration of surfactants was determined. After the viscosity tests, it was observed that the viscosity of silver nanofluid, at a concentration of surfactant 25% w/w of the nanoparticles, decrease by 2.2% in 15 and 4.6% in 30 compare to 5% surfactant concentration. Clearly, in surfactant concentration 25% w/w of the nanoparticles, viscosity have lowest value that could be due to better separation of the nanoparticles in the base fluid and better flowing movement. As well as, the experimental data of viscosity compare with the most applicable theory models for low concentration. It was found that, the experimental data have good comparison to theory data.

polyvinylpyrrolidone, surfactant, silver nanofluid, viscosity