Asymmetric flow of a nanofluid between expanding or contracting permeable walls with thermal radiation

Abstract

In the present study, the flow and heat transfer characteristics of a nanofluid in an expanding or contracting porous channel with different permeabilities in presence of thermal radiation are investigated. Analytical solutions for the flow variables are obtained by employing homotopy analysis method (HAM). Maxwell-Garnetts and Brinkman models are considered to calculate the thermal conductivity and the viscosity of nanofluid. In this investigation, we considered water and ethylene glycol as base fluids and silver (A), copper (Cu), titanium dioxide (TiO2) and alumina (Al2O3) as nanoparticles. The effects of various emerging parameters on axial velocity, temperature, shear stress and Nusselt number distributions have been discussed. The results of present study are compared with the numerical solutions obtained by shooting technique along with Runge-Kutta fourth order scheme. We found that there is a good agreement between the analytical and the numerical solutions.