Thermomagnetic convection of oxygen in a square enclosure under non-uniform magnetic field

The effects of magnet position and magnet strength on the thermomagnetic convection of gaseous oxygen in a square enclosure under combined magnetic and gravity fields are numerically studied. The magnetic field is provided by a Neodymium-Iron-Boron permanent magnet which has a high magnetic energy product. The results show that the thermomagnetic convection is significantly affected by the relative location of the permanent magnet. Both the heat transfer and buoyancy driven flow near the lower part of the vertical hot wall are greatly enhanced when the magnet is placed near the hot wall. The largest local Nusselt number is enhanced by 152.7% for the studied largest magnet strength. The corresponding largest average Nusselt number also increases by 17.9%. The overall heat transfer increases with the increase of magnet strength when the magnet is placed near the hot wall, while the heat transfer increases first and then decreases with the increase of magnet strength when the magnet is placed near the cold wall. Optimal position of permanent magnet exists for best heat transfer enhancement.