Heat transfer in water under strong gradient magnetic fields

Heat transfer in water was visually investigated using a liquid-crystal sheet with thermochromism in a hybrid magnet. Upward thermal convection was significantly suppressed by gradient magnetic fields, however, it remained even under magnetic levitation conditions with a gradient field of B(dB/dz)=-1360 T² m^-1. A thermal conduction state without convection was realized under a stronger gradient field of B(dB/dz)=-2880 T²m^-1 at 35-40°C, and surprisingly the downward magnetic convection was observed under the same field at 40-45°C. The temperature dependence of the magnetic susceptibility of water is responsible for the convection behavior in the gradient fields.