This study numerically investigates the impinging cooling of porous metallic foam heat sink. The analyzed parameters ranges comprise epsilon = 0.93/10 PPI Aluminum foam, L/W = 20, Pr = 0.7, H/W = 2-8, and Re = 100-40,000. The simulation results exhibit that when the Re is low (such as Re = 100), the Nu(max) occurs at the stagnation point (i.e. X = 0). However, when the Reynolds number increases, the Nu(max) would move downwards, i.e. the narrowest part between the recirculation zone and the heating surface. Besides, the extent to which the inlet thermal boundary condition influences the prediction accuracy of the Nusselt number increases with a decreasing H/W and forced convective effect. The application ranges of H/W and Re that the effect of the inlet thermal boundary condition can be neglected are proposed. Lastly, comparing our results with those in other studies reveals that the heat transfer performance of the Aluminum foam heat sink is 2-3 times as large as that without it. The thermal resistance is also 30% less than that of the plate fin heat sink for the same volumetric flow rate and the 5.3 mm jet nozzle width. Therefore, the porous Aluminum foam heat sink enhances the heat transfer performance of impinging cooling. (c) 2005 Elsevier Ltd. All rights reserved.