The present study deals with CFD analysis of laminar forced convective heat transfer of Al2O3/water nanofluid in a converging microchannel heat sink under imposed pressure difference. A novel approach for numerical treatment of nanofluid flow and heat transfer problems was discussed and examined. A boundary condition for partial slip flow due to deposition of nanoparticles was developed and verified. The governing differential equations were solved using the standard finite volume method in OpenFOAM. The method and the numerical solver were hydrodynamically and thermally validated against data extracted from the previous experimental studies. According to the CFD results, two correlations for predication of Nusselt number and friction factor as a function of nanoparticle volume fraction and slip length were presented. Results of this study reveal that the simultaneous consideration of slip length with thermophysical properties of nanofluid leads to a good prediction of hydrodynamic and heat transfer behavior of nanofluid. Besides, using a surface with higher slip length minimized local entropy generation. More reduction in microchannel wall temperature was achieved when higher inlet pressure values were implemented. Furthermore, the addition of Al2O3 nanoparticles to the base fluid improved heat transfer performance, but decreased hydrodynamic efficiency of the system. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.