Viscous Dissipation Impact on Free Convection Flow of Cu-water Nanofluid in a Circular Enclosure with Porosity Considering Internal Heat Source

In this work, free convection of Cu-water nanofluid in an enclosure by considering internally heat generated in the porous circular cavity and the impacts of viscous dissipation are numerically evaluated by control volume finite element method (CVFEM). The outer and inner sides of the circular porous enclosure are maintained at a fixed temperature while insulating the other two walls. The impacts of diverse effective parameters including the Rayleigh number, viscous dissipation, and nanofluid concentration on features of heat transfer and fluid flow are examined. Moreover, a new correlation for the average Nusselt number is developed according to the study’s active parameters. It can be deduced by the results that the maximum value of the temperature is proportional to the viscous dissipation parameter

Free convection of Al2O3-water nanofluid inside a hexagonal-shaped enclosure with cold diamond-shaped obstacles and periodic magnetic field

The hydrothermal characteristics of fluid flow within a hexagonal enclosure hold immense significance due to their wide-ranging applications in various fields. Despite their potential importance, there is currently a limited understanding of free convection flow within these geometries. This study aims to tackle this aspect by considering the effect of cold diamond-shaped obstacles and periodic magnetic field. The cavity top inclined walls are uniformly heated while bottom inclined walls are considered as heaters. The straight top and bottom walls of the cavity are adiabatic. The numerical solution is obtained via finite element method. The results indicate a substantial augmentation of streamlines, x- and y-direction velocities, entropy and average Bejan number with increase in the Rayleigh number. Inducing stronger magnetic field force reduces x- and y-direction velocities, average Bejan number and entropy generation. The average Nusselt number improves by 76.16% for Rayleigh number ranging from 105 to 106 at several lengths of hot surface. Among the cases analyzed in this research, moving the diamonds from the middle (Case A) to top (Case B) and bottom (Case C) enhances and reduces the Nusselt number by 6.3% and 7.5%, respectively