NUMERICAL INVESTIGATION OF BROWNIAN MOTION EFFECT ON NANOFLUID MIXED CONVECTION IN ENCLOSURE WITH A HOT CENTRAL HEAT SOURCE

This paper presents a numerical study on the mixed convection in an enclosure، with a heat source at its center filled with a water–CuO nanofluid. Central heat source and the wall heat source have Th and Tc respectively. For this purpose we used a Fortran program based on Finite Volume Method and SIMPLER algorithm. The effects of parameters such as volume fraction for 0، 0. 02 and 0. 04، Richardson number for 0. 01، 0. 1، 1، 10 and 100، Grashof equal to 104، as well as aspect ratio 0. 2، 0. 4 and 0. 6 are examined. The results show that the Nusselt number decrease with Richardson number for all aspect ratio with and without Brownian motion effects. At Richardson number equal to 100 average Nusselt number increase with volume fraction while at other Richardson number it increase from 0 to 0. 02 and it has not change after 0. 02. When we consider the effect of Brownian motion average Nusselt number show grater increase at all cases under study. Maximum increase in average Nusselt number is 9. 31 with effect of Brownian motion.