A numerical analysis is performed to study the fluid flow, heat transfer and entropy generation inside a cavity with an internal heat generation. The cavity is filled with two layers of nanofluid (TiO2-water) and one center layer of saturated porous media filled with the same nanofluid. The uniform constant heat flux is applied partly at the left vertical wall. Finite element method based on the variational formulation is employed to solve the main equations. Comparisons with previously published works are performed and the results are found to be in a good agreement. In this study, the effect of the main pertinent parameters, such as: Rayleigh number (10(4) <= Ra <= 10(7)), nanoparticles volume fraction (0 <= Phi <= 0.1), Darcy number (10(-1) <= Da <= 10(-3)), heat generation constant (0 <= lambda <= 20), and porous layer thickness (L-pm) on the fluid flow, heat transfer and entropy generation are investigated. Two different cases depending upon the location of the heat source are studied. The results indicate the heat transfer for the case-2 is better than for the case-1. The ratio of the average Nusselt number for the case-2 to the case-1 increases as the L-pm increases (the ratio is 1.365, 1.385 and 1.387 for L-pm = 0.2, 0.333 and 0.466 respectively at Ra = 10(6), Phi = 0.05, Da =10(-3) and lambda = 10). (C) 2016 Elsevier Ltd. All rights reserved.