Natural convection and entropy generation of a nanofluid around a circular baffle inside an inclined square cavity under thermal radiation and magnetic field effects

Abstract

A numerical investigation of the free convection of the Al2O3/water nanofluid was carried out in a square cavity. The cavity was tilted and exposed to a constant horizontal magnetic field. Radiation also occurred in the cavity, and entropy generation was also investigated. The left-hand and right-hand walls of the cavity were kept at a fixed temperature (Tc), while the upper and lower walls were insulated. A circular baffle with a radius of R and a temperature of Th was placed in the middle of the cavity. According to the results, amplifying the Rayleigh number (Ra) improved the Nusselt number (Nu) by 4.5 times. Amplifying the Ra also promoted entropy generation but diminished the Bejan number (Be). The heat transfer rate and generated entropy increased also by amplifying the aspect ratio. An amplification of the Hartmann number (Ha) reduced the heat transfer rate and generated entropy by 45% and 35%, respectively. Furthermore, Be was also augmented by growing the Ha. The maximum entropy generation and Be were observed at 0 and 60° inclination angles, respectively. Incorporating heat transfer by radiation and adding nano-particles to the base fluid increased both the heat transfer rate and entropy generation.