Experimental study on the magnetic convection in a vertical cylinder

The flow of paramagnetic fluid inside a cylinder placed in a bore of a superconducting magnet was studied experimentally. single-phase closed thermosyphon configuration was employed. The lower side wall of the cylindrical enclosure was heated while the upper side wall was cooled with the thin adiabatic interface in between. The experiment was carried out with an aqueous solution of glycerol. The magnetic susceptibility of the working fluid was increased by adding Gd(NO3)(3) x 6H(2)O and was measured by a magnetic susceptibility balance. The encapsulated liquid crystal slurry (KWN-2025, Japan Capsular Product Inc.) dispersed in the working fluid was illuminated in the middle height horizontal cross-section of the enclosure to visualize the temperature field. The color images of flow mode were taken by a digital camera. The average heat transfer rates were also measured. Depending on the Rayleigh number, different spoke patterns were observed. The number of angular structures (spokes) increased with increase not only in the Rayleigh number but also in the strength of magnetic field. The heated fluid was repelled by the magnetic field, while the cooled fluid was attracted. The magnetic field enhanced the heat transfer rate. (c) 2005 Elsevier Inc. All rights reserved.