A numerical investigation of the two-dimensional, laminar forced-convection cooling of heat-generating obstacles mounted on adiabatic walls in a parallel-plate channel is presented. The effect on heat transfer of insertion of a porous matrix between the blocks is considered. The Darcy-Brinkman-Forchheimer model is used to model the flow inside the porous domain. Temperature and velocity distributions in the problem domain for incompressible, laminar, and steady flow are simulated by solving governing equations numerically for appropriate boundary conditions. A computer program based on the SIMPLE algorithm is developed. The local Nusselt number at the walls of the blocks, mean Nusselt number, and maximum temperature in the blocks are examined for different Reynolds numbers, Darcy numbers, and porous-layer thicknesses. The results show that heat transfer can be enhanced by using high-thermal-conductivity porous inserts. With insertion of heated elements and porous matrix, the pressure drop increases rapidly along the channel with increase of Reynolds number.