On the Cooling Process of Nanofluid in a Square Enclosure with Linear Temperature Distribution on Left Wall

In the present paper the problem of natural convection of Al2O3-water nanofluid with consideration of variable properties inside a square cavity with different linear temperature distribution on the left wall is investigated numerically. Effects of variations of Rayleigh number, temperature distributions, and volume fraction of nanoparticles on flow and temperature field and rate of heat transfer are studied. The obtained results show that as the temperature distribution on the left wall varies, the flow and temperature patterns inside the cavity vary too. Moreover the existence of the nanoparticles in the base fluid enhances or reduces the average Nusselt number depending on the Rayleigh number and value of the nanoparticles concentration. It is found that at convection dominated regime (Ra=10^5 and 10^6), high values of nanoparticles volume fraction motivated the rate of heat transfer to decreases. When the lower end of left wall is cooled and its temperature increases by moving toward the top, a higher Nusselt number is obtained.