Effect of Nanofluid Variable Properties on Natural Convection in a Square Cavity Using Lattice Boltzmann Method

Abstract

In this paper, laminar natural convective of a nanofluid in a square cavity is studied using Lattice Boltzmann Method (LBM). The main objective is to investigate the effects of variable thermal conductivity and dynamic viscosity models for Al2O3–water and TiO2–water nanofluids on flow and heat transfer in this geometry. Hydrodynamics and thermal fields are coupled using the Boussinesq approximation. The influence of pertinent parameters such as solid volume fraction of nanoparticles (0≤φ≤5%), Rayleigh number (Ra =103-106) and the type of nanoparticles on flow and heat transfer are investigated. Good agreement was observed between the present results and those of previous numerical simulation and experimental published work. It is found that fluid flow and temperature field are affected by addition of nanoparticles into water especially for higher Rayleigh numbers. It is indicated that average Nusselt number was more sensitive to the viscosity models than to the thermal conductivity models. A deterioration of the mean Nusselt number was also observed with increasing volume fraction of the nanoparticles for the whole range of Rayleigh number.