Magnetic field effects on natural convection flow of a nanofluid in a horizontal cylindrical annulus using Lattice Boltzmann method

Effect of static radial magnetic field on natural convection heat transfer in a horizontal cylindrical annulus enclosure filled with nanofluid is investigated numerically using the Lattice Boltzmann method (LBM). The inner and outer cylinder surfaces are maintained at the different uniform temperatures. The surfaces are non-magnetic material. The investigation is carried out for different governing parameters namely, Hartmann number, nanoparticle volume fraction and Rayleigh number. The effective thermal conductivity and viscosity of nanofluid are calculated using the Maxwell-Garnetts (MG) and Brinkman models, respectively. The results reveal that the flow oscillations can be suppressed effectively by imposing an external radial magnetic field. Also, it is found that the average Nusselt number is an increasing function of nanoparticle volume fraction and Rayleigh number, while it is a decreasing function of Hartmann number. (C) 2012 Elsevier Masson SAS. All rights reserved.