Numerical Study of the Mixed Convection in a Cavity with a Movable Cap and Baffle Containing Aluminum Oxide / Water Nanofluid

In this study, mixed convection inside a square cavity with a movable cap and baffle was simulated numerically using the finite volume method. The under-study cavity was two dimensional and affected by gravity and rotated perpendicular to the plane. Right and left walls of the cavity were adiabatic and the upper wall was warm source at a constant temperature. Lower surface was a movable cap that moved from the center to both sides and was assumed to be a cold source at constant temperature. The baffle was assumed to be at the same temperature as cold wall and had a height equal to two thirds of the side of the cavity. Experimental data was used for the thermal conductivity coefficient of the nanofluid. Simulations were performed at a constant Reynolds number to investigate the effects of three parameters of Richardson number, volume fraction of solid particles and cavity slope angle on isothermal lines, streamlines and mean Nusselt value, which created 36 different states. It was found that increasing of slop angle of cavity with respect to reference surface (0 to 90 deg), increasing Richardson number (0.01 to 100) and increasing the volume fraction (0 to 0.05), increase the mean Nusselt value, where the maximum value of which is equivalent to state , , . Increasing the volume fraction of the nanofluid causes an increment in average Nusselt number. It was also observed that at low Richardson values, cavity slope angle has no effect on the results.