Forced convective heat transfer around a circular cylinder using nanofluids has been numerically analyzed employing a mixture model based Multi-Phase Modeling (MPM) approach. A hot circular cylinder with a constant wall temperature is exposed to a free stream of Al2O3-H2O nanofluid at ambient temperature. The flow is steady, laminar and two dimensional in the Reynolds number range of 10 <= Re <= 40. The governing equations of flow and energy transfer along with the respective boundary conditions are numerically solved using a Finite Volume Method (FVM) based on SIMPLE algorithm, The prime aim of this work is to highlight the effects of slip velocity, volume concentration and diameter of nanoparticles on heat transfer characteristics of nanofluids. Results indicate that heat transfer increases with increase in nanoparticle volume fraction. The highest mean Nusselt number is observed at phi = 5% at any Reynolds number. It is also noted that, nanofluids with smaller nanoparticles result in higher heat transfer rates. Particular attention has been paid to the variation of heat transfer characteristics when the modeling approach is switched from Single-Phase Modeling (SPM) to mixture model based MPM. It is revealed that higher heat transfer rates are observed in MPM which considers the effects of slip velocity. (C) 2016 Elsevier Ltd. All rights reserved.