A STUDY OF THE EFFECT OF TRANSVERSE MAGNETIC FIELD ON THE ROTATION OF A SOLID SPHERE IN A VISCOUS FLUID BOUNDED BY A CONCENTRIC SPHERICAL POROUS MEDIUM

摘要

The investigation has been done to study the effect of transverse magnetic field on the flow of a viscous fluid in a spherical annulus formed by a solid sphere rotating with a constant angular velocity and a concentric spherical porous medium for small Reynolds numbers. The Navier-Stokes equation and Brinkman equation of motion have been used for the annular region and for the porous medium, respectively. At the interface the conditions suggested by Ochoa-Tapia and Whitaker has been used. The effect of transverse magnetic field is to increase the rotational velocity in the porous medium. Simultaneous effect of the d, width of the annular region, and magnetic field has been shown graphically. The effect of magnetic field is to increase the torque on the rotating sphere.