Magnetic field effect on cooling of the magnetizable plate in magnetic fluids

V. V. Gogosov¹ - Kh. D. Iskanderov² - V. V. Kiryushin¹ - A. Ya. Simonovskii²

¹ Institute of Mechanics of the M.V.Lomonosov Moscow State University, 117192, Moscow, Russia
² Academy of Stavroplol, 355014 Stavroplol, Russia

Abstract
The temperature field on the surface of the magnetizable ball cooling in the magnetic fluid is measured by the thermocouples mounted at the different points on the ball surface and inside of the ball. The external magnetic field of varying Intensity is applied. It is shown that the temperature distribution on the ball surface is nonuniform and depends on the external magnetic field magnitude and the alignment of the points of the ball surface relative to the external magnetic field vector. It is found that the most intensive cooling occurs in the regions of the ball poles where the magnetic fluid is pressed against the ball surface bymagnetic forces. These regions are near the points where the angle q between the external magnetic field direction and the radius-vector is equal to 0 or 180 °C. The least intensive cooling occurs in the region of equator where the magnetic forces pull the magnetic fluid from the ball surface. Here the surface is separated the magnetic fluid by a vapour layer. The angle q in this region is equal to 90 °C. The problem of the temperature field distribution inside the ball is solved with a computer. The temperature values in the six points of the ball surface found In experiments have been used as the boundary conditions. The temperature values in the Intermediate points is obtained by extrapolation. The graphs describing distribution of the temperature inside the ball versus the radius r and the angle q are presented. It is found that the dependence of the temperature versus radius r smooths out rapidly in the bulk of the ball in cooling time of the order of 0.1 c. At the depth of 1 mm from the ball surface the temperature becomes practically uniform up to the center of the ball. The reading of the thermocouple mounted inside the ball confirm the theoretical results. It is found that the temperature profile tends to the same value independent of the radius r as q tends to 90 0C. Figs 7, Refs 12.