Irreversibility analysis for the natural convection of Casson fluid in an inclined porous cavity under the effects of magnetic field and viscous dissipation

The non-Newtonian fluids are increasingly being employed in various engineering and industrial processes. The Casson fluid model is also used to characterize the non-Newtonian fluid behavior and has great importance in polymer processing industries and biomechanics. Motivated by these developments, the present study explores the entropy generation for the natural convection of Casson fluid in a porous, partially heated square enclosure considering the effects of horizontal magnetic field, cavity inclination and viscous dissipation. The bottom wall of the enclosure is considered partially heated, whereas the left and right walls are taken as cold at constant temperature. The top wall and the remaining portions of the bottom wall are adiabatic. The dimensionless form of the governing conservation laws is simulated via higher order Galerkin finite element method. Particularly, the discretization is performed using biquadratic elements for velocity and temperature components whereas the discontinuous linear elements employed for the pressure. The discretized nonlinear systems are handled by implementing the adaptive Newton-multigrid solver. In order to increase the reliability of the computed results, the designed solver is validated qualitatively and quantitatively for the available numerical and experimental data. The simulated results are analyzed through isotherms, streamlines and two dimensional plots. Moreover, the average entropy generation, kinetic energy and temperature are also computed and analyzed. The controlling parameters are Hartmann number (Ha = 0 - 100), Darcy number (Da = 10-4), Prandtl number (Pr = 7), Rayleigh number (Ra = 10(5)), Casson fluid parameter (y = 0.1 - 10), cavity inclination (Phi = 0 - 90 degrees) and Eckert number (Ec = 10(-6) - 10(-4)). It is concluded that the average heat transfer rate decreases whereas the total entropy generation increases by increasing the cavity inclination (0) for each value of Ha. Further, the irreversibilities due to heat transfer and magnetic field both are increasing for function of Phi.

Automated summary

This study focuses on the numerical simulation of natural convection and entropy generation of Casson fluid in a partially heated square enclosure. The results show that increasing the cavity inclination leads to a decrease in average heat transfer rate and an increase in total entropy generation.