Numerical Study of the Effects of Geometric Parameters on Ferrofluid Mixed Convection in a Porous Rectangular Vented Enclosure

In this article we look at the effects of cavity properties on mixed convection in ferrofluid within a rectangular porous medium with a heater for the bottom wall with three current carrying wires within generating a non-uniform magnetic field, and to compare the heat transfer performance of magnetite-water/ethylene glycol (Fe \(_3\) O \(_4-\) H \(_2\) O/EG) and awaruite-water/ethylene glycol (Ni \(_3\) Fe −H \(_2\) O/EG) ferrofluids. The Darcy-Brinkman-Forchheimer model was used to describe the ferrofluid flow through the porous medium and derive the governing system of non-linear equations, which was solved using the finite difference method. Graphical results for the streamlines, isotherms and Nusselt number were generated using MATLAB R2022a. We find that the sizes of the circulation zones near the bottom heated wall increase relative to the height of the cavity, and a decrease in the inlet width increases the size of all circulation zones. With regards to the heat transfer, increasing the cavity height or decreasing the inlet width increases the overall temperature of the fluid. It was also found that decreasing the cavity height, or increasing the inlet width enhances the local Nusselt number on the heated wall. In the square case the heat transfer near the inlet was greater for the Fe \(_3\) O \(_4\) ferrofluid than the Ni \(_3\) Fe ferrofluid; in the non square cases however, the Ni \(_3\) Fe ferrofluid has greater heat transfer at the heated wall than the Fe \(_3\) O \(_4\) ferrofluid.