An experimental investigation of rheological characteristics of non- Newtonian nanofluids

Document Type : Full Lenght Research Article


1 Faculty of Mechanical Engineering, Semnan University, Semnan, Iran

2 Materials and Energy Research Center (MERC), Karaj, Iran


Rheological characteristics of Al2O3, CuO and TiO2 nano particles were investigated in oil as
the base fluid at 1 and 2 wt.%. Constitutive relations for non-Newtonian fluid were discussed
based on the power-law model. Measured viscosities of each nanofluid were used to evaluate
the power-law and consistency index. Results indicated that the nanofluid viscosity decreased
by increasing the concentration. Oil showed shear thickening behavior while nanofluids showed
shear thinning behavior. An increase in nano-particle concentration caused a decrease in the
power-law index beside an increase in the consistency index. Moreover, the present study
showed that the effective viscosity of fluids would be decreased by nanoparticle addition at
some wt.% and some shear rates. Furthermore, results showed that the classic models for
nanofluid viscosity couldn’t predict their real values of nano fluid viscosity, as the measured
values are less than the predicted ones.


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