In this article, transient hydrodynamic and heat-transfer behavior of Newtonian fluid flow in vertical parallel-plate channels partially filled with a porous medium has been investigated numerically. In this regard, the influences of macroscopic local inertial term and the viscous heating due to the viscous dissipation were taken into account in the momentum equations of porous region and the thermal energy equations, respectively. Moreover, Forchheimer-Brinkman extended Darcy model was used to model fluid flow in the porous region. In addition, an analytical solution was obtained in the case of negligible Brinkman and Forchheimer number value; at the steady-state conditions. The predicted results were compared with those predicted by a two-parameter perturbation technique developed by the present authors at the steady-state conditions and good agreement was obtained. The predicted results clearly indicate that neglecting the inertial effect in high permeability porous media or high velocity flows can alter substantially the flow and heat transfer characteristics. (C) 2012 Elsevier Ltd. All rights reserved.