Effect of the thermal boundary conditions and physical properties variation on transient natural convection of high Prandtl number fluids (original) (raw)

This work presents numerical analysis of effects of thermal boundary conditions, fluid variable viscosity and wall conduction on transient laminar natural convection of high Prandtl number (P r = 10 4 ) fluid (Golden Syrup) in a cubical cavity. The simulations consider the flow in a cavity with Plexiglas walls of 1cm of thickness, the inside dimension of the cavity is L = 20cm. The initial Rayleigh (Ra) number is 10 6 , the cavity is initially full of fluid at rest and at constant temperature (Ti = 45 o C) higher than the temperature of the walls (Tw = 25 o C). The time evolution of the flow patterns, the temperature contours, the mean temperature of the fluid and the Nusselt number (Nu) for four different cases of cooling are presented and analyzed.