Periodic fully developed fluid flow and heat transfer characteristics are obtained numerically for turbulent flow over three-dimensional arrays of heated square blocks deployed along one wall of a parallel-plate duct. This configuration simulates forced convection cooling of electronic equipment. The high Reynolds number form of the k-epsilon turbulence model is used for the computations. The computations are performed for the condition of uniform wall temperature, for a wide range of geometric parameters characterizing the array, for a range of Reynolds numbers from 10(4) to 10(5), and for Prandtl number of 0.7. The results show that the friction factor is higher or lower than the values obtained from an empirical correlation for a parallel-plate duct depending on the geometric parameters and the Reynolds number. The cycle averaged Nusselt number is also higher or lower than the analytical values for a parallel-plate duct with one wall heated at a constant rate and the other wall insulated depending on the geometric parameters and the Reynolds number.