NATURAL CONVECTION IN NANOFLUID-FILLED SQUARE CHAMBERS SUBJECTED TO LINEAR HEATING ON BOTH SIDES: A NUMERICAL STUDY

Abstract

Buoyancy-driven heat transfer in two-dimensional nanofl uid-fi lled square enclosures with linear temperature profi le on the side walls and adiabatic horizontal walls is studied numerically. Numerical simulations are performed for Rayleigh numbers ranging from 103 to 106 , the volume fraction of the nanoparticles ranging from 0 to 0.06, and for three different combinations of the temperature distribution on the side walls. The results are presented in terms of streamlines and isotherms inside the cavities, local Nusselt number along the left wall, and average Nusselt number of the hot portions of the side walls. The results show that the flow and temperature fields inside the cavity vary significantly when the temperature profile on the side walls of the cavities is changed. At Ra = 103 the fl ow intensity is shown to decrease with increasing volume fraction of the nanoparticles, while at Ra = 106 it is not the case. The values of the maximum and minimum local Nusselt number at the ends of the left wall are shown to increase with increasing Rayleigh number and volume fraction of the nanoparticles. Moreover, along the both heating and cooling portions of the left wall, the increase in the volume fraction of the nanoparticles enhances the rate of heat transfer.