The unsteady mixed convection boundary layer flow near the stagnation point on a heated
vertical plate embedded in a fluid saturated porous medium is studied. It is assumed that
the unsteadiness is caused by the impulsive motion of the free stream velocity and by sudden
increase in the surface temperature. Both the buoyancy assisting and the buoyancy
opposing flow situations are considered with combined effects of the first and second order
resistance of solid matrix of non-Darcy porous medium, variable viscosity and radiation.
The problem is reduced to a system of non-dimensional partial differential equations,
which is solved numerically using the Keller-box method. The features of the flow and
the heat transfer characteristics for different values of the governing parameters are analyzed
and discussed. The surface shear stress and the heat transfer of the present study
are compared with the available results and a good agreement is found.