Effect of buoyancy and suction on Sisko nanofluid over a vertical stretching sheet in a porous medium with mass flux condition

Abstract

The present article investigates the flow and heat transfer of Sisko nanofluid over a permeable vertical stretching surface in a porous medium. The effect of buoyancy, suction, and viscous dissipation has been taken into account. Buongiorno’s model of nanofluid consisting of thermophoresis and Brownian diffusion has been considered. Moreover, zero nanoparticle mass flux condition is employed at the boundary which leads to a more realistic physical problem. Using a suitable transformation governing partial differential equations of fluid flow are transformed into a set of nonlinear ordinary differential equations (ODEs). The numerical solution of nonlinear ODEs are obtained using the finite difference technique in MATLAB. The influence of physical parameters viz. buoyancy parameter (λ*), porosity parameter (β*), thermophoresis parameter (Nt*), suction parameter (f), Sisko material parameter (A*), Brinkman number (Br*), Brownian diffusion parameter (Nb*) and Lewis number (Le*) on velocity, temperature and nanoparticle volume fraction are shown graphically. Moreover, to understand the physical phenomenon in the boundary layer region, the numerical values of skin friction and Nusselt number are calculated and presented through table values. It has been found that the Brownian diffusion has a negligible impact on Nusselt number relative to the results obtained in previous studies, where nanoparticle volume fraction on the boundary was actively controlled. The obtained results disclose that the buoyancy parameter increases the velocity of fluid while it reduces the temperature. Suction parameter reduces both velocity and temperature, whereas the porosity parameter reduces velocity and enhances the temperature and nanoparticle volume fraction.