Conjugate Natural Convection in a Partitioned Square Cavity Filled with Al2O3-Water Nanofluid Based on Experimental Correlations: a Lattice Boltzmann investigation

Abstract

In this paper a numerical investigation of conjugate natural convection inside a divided square cavity filled with Al2O3-water nanofluid is performed. The lattice Boltzmann method (LBM) is used to solve the governing equations. The nanofluid thermo-physical properties are selected based on literature experimental correlations. The grid independency was checked and the LBM code model was validated on two different cases for wide ranges of the present problem monitoring parameters. A good agreement is obtained by comparison with reported results in the literature. The study of the conjugate heat transfer and nanoliquid motion is, afterward, conducted for the ranges of nanoparticles volume fraction (%): 1 ? ?? 4, temperature (°C): 20 ? T? 40, particle size (nm): 15? dp?120 and Rayleigh number: 103 ?Ra ? 106. It will be shown firstly that, at room temperature, the viscosity and the thermal conductivity experimental correlations based models give results in strong deviation compared to theoretical ones. The effects of the aforementioned problem parameters on local and average heat transfer and velocity profiles are explored and discussed. Results show a heat transfer rise by increasing the temperature. However, for the Al2O3 nanoparticles size, the enhancement marked a maximum close to dp=33nm in a concave behavior. The heat transfer and the fluid motion are dumped by increasing the volume fraction ? (%) and the nanoparticles size (dp ?35nm) due to the reduced effective Ra* number.