HALL EFFECTS ON UNSTEADY FLOW DUE TO NON-COAXIALLY ROTATING DISK AND A FLUID AT INFINITY

Abstract

An investigation is made on the unsteady magnetohydrodynamic (MHD) flow caused by the non-coaxial rotation of a disk and a fluid at infinity being permeated by a transverse magnetic field. The disk is porous and nonconducting and executes oscillations in its own plane. The Laplace transform method is used to obtain the exact solution of the velocity field. The structure of the steady and unsteady flow fields is investigated. It is shown that the ultimate steady-state blowing solution is established in the presence of Hall current also for resonant frequency, which was not possible in the hydrodynamic case. The combined effects of Hall current, rotation, and suction or blowing are examined. The physical significance of mathematical results is given with various limiting cases.

Keywords:

• Exact solution
• Hall effect
• Oscillating porous disk
• Resonance
• Unsteady flow

Acknowledgments

The authors are grateful to the anonymous referees for their constructive suggestions. T. Hayat is also grateful to the Higher Education Commission (HEC) of Pakistan for the financial support. SA and RE gratefully acknowledges the warm hospitality of the Fluid Mechanics Group (FMG) of the Department of Mathematics, Quaid-i-Azam University 45320, Islamabad. They in particular thank Prof. T. Hayat for his kind invitation and congratulates him for his selection as a Distinguished National Professor of the HEC and fellow of Pakistan Academy of Science.