Abstract
In this analysis, the magnetohydrodynamic boundary layer flow of Casson fluid over a permeable stretching/shrinking sheet in the presence of wall mass transfer is studied. Using similarity transformations, the governing equations are converted to an ordinary differential equation and then solved analytically. The introduction of a magnetic field changes the behavior of the entire flow dynamics in the shrinking sheet case and also has a major impact in the stretching sheet case. The similarity solution is always unique in the stretching case, and in the shrinking case the solution shows dual nature for certain values of the parameters. For stronger magnetic field, the similarity solution for the shrinking sheet case becomes unique.