CFD Analysis of Mixed Convection in an Enclosure with a Floor-Mounted Step-Like Heat Source

Abstract

The objective of this work is to study the two-dimensional mixed convection flow and heat transfer over an isoflux step projecting from the floor of an enclosure. The inflow into the enclosure takes place through two inlets placed at either end of the floor and the outflow occurs through an outlet provided in the ceiling of the enclosure. The walls of the enclosure are insulated. Convective heat transfer from the step surfaces to the fluid occurs due to the combined action of forced and free convection effects. The heat transferred to the fluid is carried away by the fluid leaving the enclosure. A mathematical formulation is developed by setting up the conservation equations for mass, momentum and energy, and the initial and boundary conditions. The density variation is taken into account only in so far as it gives rise to a buoyancy force. The equations are non-dimensionalised so that the results will have applicability to wide-ranging practical conditions. A numerical formulation is developed by discretising the primitive variable equations on a staggered mesh, using the ultra-sharp strategy for convection terms with donor-cell differencing scheme option, the modified strongly implicit procedure (MSIP) as the equation solver and the Simplified Marker and Cell (SMAC) method as the pressure-velocity coupling algorithm. Parametric studies are performed by varying the Archimedes number Ar and Reynolds number Re (while Prandtl number Pr is chosen as 0.71 corresponding to air as the working medium), and results are presented in the form of streamline and isotherm maps, graphs, and tables.