Effect of inclined magnetic field on natural convection and entropy generation of non-Newtonian ferrofluid in a square cavity having a heated wavy cylinder

Magnetohydrodynamic (MHD) natural convection of non-Newtonian ferrofluid and entropy generation in a square enclosure containing a wavy cylinder was investigated. The inner wavy cylinder was assumed to be heated and the outer square enclosure to be cold. The ferrofluid's rheology was presented by the power-law model, while density fluctuations owing to thermal expansion were described using the Boussinesq approximation. Numerical calculations had been performed using dimensionless parameters such as Hartmann number, power-law index, Rayleigh number, wave number, and volume fraction. Results are discussed in terms of isotherms, velocity field, average Nusselt number, and entropy generation, taking into account the variations in physically significant parameters. Results indicate that thermal convection dominates the isotherms of shear-thinning fluids, while conduction is more prominent in shear-thickening fluids. The power-law index (n) greatly influences the streamlines and isotherms. The non-Newtonian ferrofluid's average Nusselt number (\(\overline{\mathrm{Nu}}\)) rises as the Hartmann number is reduced and the Rayleigh number (Ra) is increased. In this simulation, the maximum value of \(\overline{\mathrm{Nu}}\) is found to be 8.38 because of the addition of ferroparticles. Additionally, the irreversibility caused by fluid friction, heat transfer, and magnetic field for the shear-thinning (n < 1), Newtonian (n = 1), and shear-thickening (n > 1) cases can be minimized by using the ideal parametric combination.