MHD natural convection in nanofluid filled square cavity with isothermally heated hexagonal block

This article explores the influence of natural convection heat transfer in a square enclosure with hexagonal block filled by Al2O3-H2O nanofluid in presence of external magnetic field. The two vertical walls of the enclosure are kept at constant cold temperature, Tc, and the top horizontal wall is insulated whereas the remaining walls of the enclosure are maintained high temperature, Th. The governing equations are formulated using Boussinesq approximations and solved numerically employing built-in-finite element method and then presented graphically in terms of streamlines, isotherms, average Nusselt number and average temperature. It is found that the different values of physical parameters: Rayleigh number (Ra = 103 -106), nanoparticle volume fraction (ϕ = 1% -5%) and Hartman number (Ha = 0-100) affects the streamlines, isotherm contours and heat transfer rate. Comparison of the present results with previously published results on the basis of special cases has been performed and found to be a good agreement.