Viscosity of water based SWCNH and TiO2 nanofluids

At present, literature data on viscosity of nanofluids are still scarce and controversial. The possible non-Newtonian behaviour of these fluids is frequently neglected and the problems related to the nanofluids stability and the actual composition are often not considered. In this paper, viscosity data for nanofluids formed by water, as base fluid, and solid nanoparticles of two different materials – single wall carbon nanohorn (SWCNH) or titanium dioxide (TiO2) – are presented. Viscosity was measured by using a rheometer and obtained as a function of the nanoparticles mass fraction and the shear rate, thus allowing evaluation of the possible non-Newtonian behaviour for the nanofluid. Both the studied nanofluids showed a Newtonian behaviour.The viscosity data were correlated by different equations and here an empirical correlation is proposed.

► Viscosity for H2O–SWCNH and H2O–TiO2 nanofluids was measured by a rheometer.
► Nanoparticles mass fractions up to 1% and different shear rates were considered.
► Both the studied nanofluids showed a Newtonian behaviour.
► Negligible viscosity increase for nanoparticles mass fractions up to 0.1% was observed.
► Significant viscosity increase for nanoparticles mass fraction of 1% was observed.