On Solutions Of Some Unsteady Flows Over A Continuous, Moving, Porous Flat Surface

A singular perturbation solution for hydromagnetic boundary-layer flow over a continuously moving surface with large suction is obtained and compared with its exact solution. Also, the solutions are obtained for finite and large values of t (time) and for various asymptotic cases. Flow of this type represents a new class of boundary-layer problems, with solutions substantially different from those for boundary-layer flow on a flat surface of finite length. Surprisingly, the inner solution of the problem is valid even in the outer region, and the effect of magnetic field on the flow field is almost negligible. Furthermore, it is shown that a straightforward perturbation expansion valid for all t (time) and y (space coordinate), for small suction, is not possible because of the infinite condition On y. © 1990