Effects of a centered conducting body on natural convection of a non-Newtonian fluid in a square enclosure with time-periodic temperature distribution

Abstract

In this paper, a modified lattice Boltzmann model that incorporates the effect of heat capacity is adopted to study the effects of a centered conducting body on the natural convection of a non-Newtonian fluid in a square cavity with time-periodic temperature distribution. The effects of power-law index, Rayleigh number, heat capacity ratio, thermal conductivity ratio, body size, temperature pulsating period, and temperature pulsating amplitude on fluid flow and heat transfer are analyzed in detail. The results showed that the increase of Rayleigh number and thermal conductivity ratio as well as the decrease of power-law index can strengthen both transient and global heat transfer, while the increase of heat capacitance of the fluid to the solid wall can enhance the transient heat transfer and has little effect on the overall heat transfer. Furthermore, the increase of body size will reduce both the transient heat transfer ratio and the overall heat transfer ratio. In addition, the decrease of temperature pulsating period can enhance the transient heat transfer, but will slightly weaken the overall heat transfer. Finally, the results show that both the transient and overall heat transfer ratios increase with the increase of temperature pulsating amplitude.