Radiation effects on Marangoni convection flow and heat transfer in pseudo-plastic non-Newtonian nanofluids with variable thermal conductivity

In this paper, we examine radiation effects on Marangoni convection flow and heat transfer in pseudo-plastic non-Newtonian nanofluids driven by a temperature gradient. The surface tension is assumed to vary linearly with temperature. Four different types of nanoparticles; namely, Cu, Al2O3, CuO and TiO2, are considered with sodium carboxymethyl cellulose (CMC)-water used as a base fluid. The effects of power-law viscosity on temperature field are taken into account by assuming that the temperature field is similar to the velocity field and that the thermal conductivity of the non-Newtonian fluids is power-law-dependent on the velocity gradient. The governing partial differential equations are reduced to a series of ordinary differential equations using similarity transformations, the solutions are obtained numerically by the shooting method. The effects of the solid volume fraction, the Power-law Number, the Marangoni Number and the Radiation Number on the velocity and temperature fields are analyzed and discussed in detail. (C) 2014 Elsevier Ltd. All rights reserved.