Effect of alumina nano-powder on the convection and the entropy generation of water inside an inclined square cavity subjected to a magnetic field: Uniform and non-uniform temperature boundary conditions

Abstract

This paper has numerically investigated the convection heat transfer and the entropy generation of water-Al2O3 nanofluid in a square cavity, under the uniform and non-uniform boundary conditions in the presence of a magnetic field. The effect of changes of Rayleigh number, Hartmann number, direction of application of magnetic field and volume percent of nanoparticles on entropy generation and heat transfer rate have been investigated. The results show that increasing the Rayleigh number of the gradient increases the temperature and Nusselt number and total entropy increase, but the Bejan number decreases. The highest average Nusselt number is associated with the sinusoidal temperature profile and the highest total entropy generation is related to the first order profile. By increasing the strength of the magnetic field, the velocity of the flow, the total entropy generation and the heat transfer rate are reduced. Increasing the angle of the field from 0 to 45° in all temperature profiles, Nusselt number increases. However, with increasing angle of the field from 45 to 90, in some temperature profiles the Nusselt number has increased, but decreases in other profiles. By increasing the volumetric percent of nanoparticles, Nusselt number and total entropy generation are also increased. This increase in second order profile is the highest and has the lowest value in the sinusoidal temperature profile. Finally, it was observed that with an increase in the entropy parameter, the total entropy generation has also increased.