Entropy analysis in nonlinearly convective flow of the Sisko model in the presence of Joule heating and activation energy: the Buongiorno model

This investigation deals with entropy generation optimization and an activation energy mechanism for nonlinear convective flow of a Sisko nanofluid due to a stretchable rotating disk. Heat transfer analysis is accomplished through nonlinear thermal radiation and non-uniform heat generation/absorption. The Joule heating effect is also considered with viscous dissipation. The nanofluid model includes Brownian motion and thermophoresis. Apposite transformations are endorsed to obtain the nonlinear-coupled ordinary differential equation system. The attained system endeavors for series solutions by the homotopy technique. Total entropy generation is analyzed through numerous flow variables. A comparative study of shear-thickening and shear-thinning fluids is also presented for the Bejan number, heat transfer rate, mass transfer Nusselt number, entropy generation, temperature, velocity and concentration. Here the entropy generation rate (irreversibility rate) is enhanced for the thermal radiation parameter while the reverse behavior is noted for the material parameter and Brinkman number. Furthermore, the behavior of the temperature profile and nanoparticle concentration will be displayed through a Brownian motion parameter and an activation energy parameter.