Attenuation of natural convection by magnetic force in electro-nonconducting fluids

We present numerical simulations of the velocity and temperature distributions of a nonconducting fluid (water) heated from below in the presence of an imposed, nonuniform magnetic field, generated with a solenoid-type magnet. The vertically placed magnet induces horizontal and vertical magnetic forces due to the gradient of magnetic strength, and the horizontal force is found to play an important role to damp natural convection. When an imposed magnetic field of strength H-0 in the middle of the magnet, is less than a critical value, H-0c, the damping effect increases with increasing H-0. For H-0 > H-0c, natural convection is completely replaced by convection induced by the magnetic field. Our results indicate a novel method to control convection of nonconducting fluids, especially in crystal formation processes. (C) 1999 Elsevier Science B.V. All rights reserved.