Abstract
In this article, radiation effects on the unsteady boundary layer flow of a micropolar fluid over a stretching sheet are reported. The sheet is considered to be permeable and the problem is nondimensionalized by using similarity transformations. The resulting problem is solved analytically by the homotopy analysis method (HAM) and different interesting flow parameters are explained through graphical results. The convergence of the obtained solutions is checked by displaying ħ-curves in which the auxiliary parameter ħ plays an important role to ensure the convergence of the series solutions.