On unsteady heat and mass transfer in Carreau nanofluid flow over expanding or contracting cylinder with convective surface conditions

In this article, we introduce the more general convective heat and mass conditions in the unsteady flow of Carreau nanofluid over an expanding or contracting horizontal cylinder in the presence of temperature dependent thermal conductivity. Appropriate transformations are used to alter the non-linear partial differential equations into ordinary differential equations. Numerical results of the resulting system are calculated by an effective numerical approach namely bvp4c function in Matlab. Effects of distinct emerging parameters on the velocity, temperature and nanoparticle concentration are analyzed. Numerical results of the local Nusselt and Sherwood numbers are also computed in tabular form. It is observed that the velocity, temperature and nanoparticle concentration are diminishing functions of the unsteadiness parameter. It is further noticed that the rate of heat and mass transfer is diminishing for growing the values of the thermal conductivity parameter in cases of shear thinning (0 < n < 1) and shear thickening (n > 1) fluids. In addition, on increasing the values of thermal Biot number, the heat transfer rate enhances but opposite behavior is noticed in mass transfer rate. (C) 2017 Elsevier B.V. All rights reserved.