This paper presents the flow and heat transfer characteristics of melting behavior of phase change material (PCM) in the presence of nanoparticles. The melting process occurs in a concentric cylindrical enclosure filled with PCM (ice) and aluminum oxide (Al2O3) nanoparticles. The inner and outer walls of the concentric cylinder are considered as hot and cold walls and maintained at a constant wall temperature. The problem is modeled as unsteady, two-dimensional turbulent multiphase flow using the Eulerian multiphase model and SST k-ω turbulence model. The numerical simulation is performed using Ansys Fluent 19.2. The primary and secondary phases are specified with thermo-physical properties of ice and aluminum oxide. The transient melting behavior of PCM is investigated for different nanoparticle volume concentrations by varying the temperature difference between the hot and cold walls of concentric enclosure. The results are analyzed by plotting the streamline, velocity and temperature contours. The results indicate that the dispersion of aluminum oxide nanoparticles into phase change material increases the heat transfer rate and decreases the melting temperature of PCM. The results also indicate that the melting rate and thermal performance are significantly enhanced with increase in volume concentrations and temperature difference. © Published under licence by IOP Publishing Ltd.