Abstract
•MHD natural convection and entropy generation of Fe3O4–water nanofluid is analyzed.•Brinkman-extended Darcy model is used for description of fluid flow in porous blocks.•The finite difference method is used to solve the governing equations.•Magnetic field and porous blocks are very good control parameters for heat transfer.
In this study, natural convection combined with entropy generation of Fe3O4–water nanofluid within a square open cavity filled with two different porous blocks under the influence of uniform horizontal magnetic field is numerically studied. Porous blocks of different thermal properties, permeability and porosity are located on the bottom wall. The bottom wall of the cavity is kept at hot temperature Th, while upper open boundary is at constant cold temperature Tc and other walls of the cavity are supposed to be adiabatic. Governing equations with corresponding boundary conditions formulated in dimensionless stream function and vorticity using Brinkman-extended Darcy model for porous blocks have been solved numerically using finite difference method. Numerical analysis has been carried out for wide ranges of Hartmann number, nanoparticles volume fraction and length of the porous blocks. It has been found that an addition of spherical ferric oxide nanoparticles can order the flow structures inside the cavity.