An Analytical Model for Determination of Nanofluids Viscosity

In this paper, the influence of the temperature, mean nanoparticle size and the nanoparticle concentration variables are investigated analytically on the dynamic viscosities of nanofluids and a modified equation for calculating the nanofluids viscosities is introduced. The new Correlation for effective viscosity is developed based on previous model in which the Brownian movement of the nanoparticles is considered as the key mechanism. However, it has been found that the application previous models not to be appropriate for nanoparticles 2Tlarger than 36 nm. Moreover, their work focused on low volume concentrations of nanoparticles up to 0.5% only. We2T 2Thave considered2T 2Tthe possibility of2T 2Thomogeneous dispersion of2T 2Tthe2T 2Tnanoparticles and have used2T 2Tthe2T 2TStokes2T 2Tlaw2T. The current model for the effective viscosity of nanofluids is 2Texplained2T in terms of temperature, the mean nanoparticle diameter, the nanoparticle volume concentration and both of nanoparticle and base fluid thermophysical characteristics. To take into account the simplification for a free stream boundary condition outside the boundary layer, a combination correction factor is introduced. Very good agreement was observed between the effective viscosity from the present model and those of published experimental for different nanofluids.

کلیدواژه ها:

Effective viscosity ، Nanofluid ، Thermophysical properties ، Volume concentration ، Mean nanoparticle diameter