Modern Status Of Researches Of Nanofluids Viscosity

In present paper the regular review of researches of nanofluids viscosity is made. Known experimental data and data of molecular dynamic simulation are considered. It is shown, that nanofluid viscosity is not described by the classical theories. All experimental data and molecular dynamics simulations suggest that at a fixed volume concentration of nanoparticles, the nanofluid viscosity is significantly higher than the viscosity of conventional suspensions. Generally it depends not only on concentration наночастиц, but also from their size. The viscosity coefficients increase with decreasing nanoparticle size. It was shown by molecular dynamics method that the viscosity coefficient of nanofluid depends on the nanoparticles material. At low and moderate concentrations of nanoparticles, the relative viscosity coefficient does not change with increasing temperature. In this case the temperature dependence of nanofluid viscosity is determined by the corresponding dependence of based fluid. The nanofluid prepared on distilled water with CuO nanoparticles has the nonNewtonian rheology if the concentration of the particles is more than 0.25 in the volume. It was established that their rheology is well described by the power law fluid model. With an increase in concentration of nanoparticles, nanofluid index decreases, but the consistency parameter K, on the contrary, increases. The correlation defining dependence of the viscosity coefficient on nanoparticles concentration and their size is offered. The reasons of nonclassical behavior of nanofluids are in detail discussed.