Numerical Simulation of Rayleigh-Bernard Convection in Enclosures Filled with Nanofluid

Abstract

Numerical investigations of Rayleigh-Bernard convection in enclosures of different modified bottom and top surfaces filled with Au-Water Nanofluid are presented. This paper describes a numerical predication of heat transfer and fluid flow characteristics inside enclosures bounded by modified bottom and top surfaces and two periodic straight vertical walls. Simulations are carried out for a Rayleigh number of 6 × 10⁴ and two aspect ratios (0.25 and 0.5) with working fluid as water (base fluid). The same analyses are performed with the Nanofluid having Au nano-particles of same size in order to see the effect of Nanofluid on heat transfer. The Boussinesq approximation is used in order to take density change effect in the governing equations. The study investigates the effect of the nanoparticle volume fraction, and the aspect ratio on the heat transfer. The results are presented in terms of isotherms, streamlines local, and average surface Nusselt numbers. Results show that the flow and isotherms are affected by the geometry shape and by the presence of nanoparticles. It is also shown that for a fixed value of aspect ratio, the convective heat transfer is decreased for the Nanofluid when compared with that of base fluid due to an increase in thermal conductivity of the Nanofluid.