INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids 2009; 60:357–363 Published online 24 July 2008 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/fld.1890 Hall effects for MHD Oldroyd 6-constant fluid flows using finite element method M. Sajid 1, ∗, † , R. Mahmood 1 , T. Hayat 2 and A. M. Siddiqui 3 1 Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad 44000, Pakistan 2 Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000, Pakistan 3 Department of Mathematics, Pennsylvania State University, York Campus, York, PA 17403, U.S.A. SUMMARY This paper numerically investigates the influence of Hall current on the steady flows of an Oldroyd 6-constant fluid between concentric cylinders. The flow analysis has been performed by employing finite element method. Two flow problems are considered. These problems have been recently solved by Rana et al. (Chaos, Solitons and Fractals, in press). Here the main equation governing the flow problems in (Chaos, Solitons and Fractals, in press) is corrected first and then used in the simulation. Finally, the interesting observations are obtained by plotting graphs. Copyright 2008 John Wiley & Sons, Ltd. Received 4 March 2008; Revised 28 May 2008; Accepted 21 June 2008 KEY WORDS: finite element method; Oldroyd 6-constant fluid; steady flows; Hall currents; Poiseuille flow; Couette flow 1. INTRODUCTION The non-Newtonian fluids are now acknowledged more appropriate in industrial and techno- logical applications. In view of their importance, several authors [1–19] have recently studied non-Newtonian fluids in various situations. Very recently, Rana et al. [20] analyzed the magne- tohydrodynamic (MHD) flows of an Oldroyd 6-constant fluid between two concentric cylinders. In fact, the conclusion that m →∞ gives the result of the hydrodynamic case is not correct. This happens due to a mistake in Equations (9), (12), (21), and (23) of Reference [20]. They discussed the Poiseuille and generalized Couette flows using finite difference scheme. In the present paper, we first correct the equations and then reconsider the Poiseuille and generalized Couette flows. The finite element method is used in finding the numerical solution. The main points of the present analysis are included in the conclusions. ∗ Correspondence to: M. Sajid, Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad 44000, Pakistan. † E-mail: sajidqau2002@yahoo.com Copyright 2008 John Wiley & Sons, Ltd.