Effect of Sinusoidal Thermal Boundary Condition on Natural Convection in a Cavity Filled with Cu-Water Nanofluid

This paper summarizes a numerical study of natural convection in a square cavity filled with water based nanofluid (water with Cu particles). The cavity used for flow and heat transfer analysis has been bounded by adiabatic top wall, constant temperature cold vertical walls and a horizontal bottom wall. The bottom wall is subjected to uniform and sinusoidal varying temperatures. The nanofluid is assumed to be incompressible and the flow is considered to be laminar. Calculations were performed for Rayleigh number (10(3) <= R-a <= 10(5)) and volume fraction of nanoparticles (0 <= phi <= 0.1). Results are presented in the form of stream lines, isotherm plots and average Nusselt numbers. It is observed from this study that the uniform temperature at the bottom wall gives higher Nusselt number compared to the sinusoidal varying temperature case for phi = 0, 0.05 and 0.1 for bottom wall. For a given Rayleigh number an increase of volume fraction of nanoparticles causes an increase of the mean Nusselt number, but this increment is high for the case of constant temperature.