Pergamon Int. Comm. tteatMass 7?ansfer, Vol.25, No. 6, pp. 899-906, 1998 Copyright © 1998ElsevierScienceLtd Printed in the USA.All rightsreserved 0735-1933/98 $19.00+ .00 PII S0735-1933(98)00075-X UNSTEADY HYDROMAGNETIC FLOW AND HEAT TRANSFER FROM A NON-ISOTHERMAL STRETCHING SHEET IMMERSED IN A POROUS MEDIUM Ali J. Chamkha Department of Mechanical and Industrial Engineering, Kuwait University Safat, 13060 KUWAIT (Communicated by J.P. Hartnett and W.J. Minkowycz) ABSTRACT This paper considers unsteady, laminar, boundary-layer flow and heat transfer of an electrically-conducting and heat-generating (or absorbing) fluid along a horizontal stretching plate at variable temperature embedded in a porous medium in the presence of a magnetic field. The governing equations are transformed and solved numerically. The obtained results for a special case of the problem are compared with previously published work and found to be in excellent agreement. A parametric study illustrating the influence of various physical parameters is performed. Numerical results for the steady-state velocity and temperature profiles as well as the time histories for the skin-friction and wall heat transfer coefficients are presented graphically and discussed. © 1998ElsevierScience Ltd Introduction The problem discussed in this paper is that of unsteady laminar flow and heat transfer of an electrically-conducting and heat-generating (or absorbing) fluid from a non-isothermal stretching semi-infinite plate adjacent to a porous medium in the presence of a uniform magnetic field. This type of flow and heat transfer situation finds application in a number of manufacturing and technological processes. Examples of these processes include glass blowing, hot rolling, extrusion of films and plates, continuous casting, cooling of metallic sheets, cooling of electronic chips, crystal growing, melt spinning and many others. 899