Lattice Boltzmann simulation of nanofluid free convection heat transfer in an L-shaped enclosure

•Nanofluid free convection in an L-shaped cavity is studied numerically.•The lattice Boltzmann method is used in the numerical simulations.•Rayleigh number, nanoparticle diameter and concentration effects are studied.•The heat transfer enhancement is higher for lower aspect ratios.•The average Nusselt number decreases with an increase in nanoparticle size.

In the present paper, fluid flow and free convection heat transfer of a nanofluid in an L-shaped enclosure is studied numerically using the Lattice Boltzmann Method. To consider the effects of Brownian motion, temperature and nanoparticle size on the nanofluid thermal conductivity, Patel et al. model is used. The effects of different parameters such as Rayleigh number (103–106), channel aspect ratio (0.2–0.6), nanoparticle volume concentration (0–0.05) and nanoparticle diameter (20–80 nm) on the flow and temperature fields are studied. The obtained results show that nanofluid enhances the heat transfer amount and reducing the channel aspect ratio improves this effect. Moreover, the average Nusselt number decreases with an increase in the nanoparticle diameter and this effect is more pronounced for higher volume concentrations.