Nanofluids are heterogeneous suspensions of nanoparticles in common fluids, which are typically called base fluids. Nanofluids exhibit significantly altered heat and mass transfer characteristics and have become the subject of investigations of numerous research projects since 1995. Several sets of experimental data indicate that the addition of very small quantities of nanoparticles in the base fluids. Nano fluids are heterogeneous media at a scale of the order of magnitude of the nanoparticle size, composed of nanoparticles immersed in the base fluid. Nano fluids are composed primarily of irregular, elongated particles and the experimentally observed Effective viscosity of these heterogeneous mixtures is higher than the analytical expressions that are based on the spherical particle model. One of the reasons for the non-Newtonian behavior of carbon nanotube nanofluids is the addition of surfactants or dispersants, which are typically polymeric materials with long molecular chains.