So far a lot of researchers have attempted to find a suitable relation to predict physical properties of nanofluids. But most of traditional formulae which belong to big size particles were not useful for nanofluids and empirical correlations also have their working condition limitations. There are several factors such as particle shape, size and material, interaction between particles, temperature, velocity, type of fluid flow, physical properties of both particle and base fluid and which affect on determination of physical properties of nano fluids. In this paper has been reviewed and classified all existing formulae and correlations about physical properties of nanofluids including thermal conductivity, viscosity, density and specific heat.
