Heat flux and convective boundary influence on nanofluid-filled cavity

Abstract

Electronic devices release heat to the atmosphere from the walls, and system miniaturisation results in exponential increase in the heat associated with these high-heat-generating/electronic devices. To analyse this numerically, heat-flux and convective types of boundary condition are considered at the walls, which are the most realistic boundary condition type. In present work, the physical model consists of nanofluid inside an enclosure with one side subjected to constant heat-flux and the other sides exposed to convective boundaries, is solved. The nanofluid is completely confined within the enclosure and flows due to natural convection. Considering the heat-flux varying from 100 W/m2 to 10 kW/m2, three (Ra) Rayleigh numbers are calculated. Results are validated with experimental results also. Results show that increasing Ra and copper nanoparticle concentration results in strengthening the heat transfer and average Nusselt number. Results also show that the thermal boundary layer thickness increases with aspect ratio (AR). Streamline contours show that natural convection strength is higher for low ARs compared to high ARs. For a low Ra (2 × 104), viscosity model is more sensitive than the thermal conductivity model, and for high Ra (2 × 106), the thermal conductivity model is more sensitive than the viscosity model.