The extended homotopy perturbation method and boundary layer flow due to condensation and natural convection on a porous vertical plate

The extended homotopy perturbation method (EHPM), which is an extension to the well-known homotopy perturbation method (HPM) due to He, is applied to derive the analytical solution of the boundary layer flow of falling vapour due to the condensation on a cold, porous vertical plate. The EHPM calculates the solution automatically by adjusting the scaling factor of the independent similarity variable normal to the plate. The results obtained by the EHPM are in excellent agreement with the exact numerical solution. Also an asymptotic solution, valid for a large suction parameter is developed which matches very well with the exact solution even for moderate values of the suction velocity. Finally, it is shown that the EHPM solution is also applicable to the moderate values of blowing across the plate.