Mixed convection and entropy generation in a nanofluid filled cubical open cavity with a central isothermal block

Three dimensional numerical simulations have been performed on a cubical cavity using finite volume method. Vorticity-vector potential formalism is enforced on the open cavity filled by the Aluminum Oxide/Water nanofluid. The cavity is heated up by the central isothermal block and the results of mixed convection and entropy generation are illustrated with particle trajectories, isotherms, Nusselt number and Bejan number. The considered parameters are Richardson number (0.01-100), block size (0.1L -0.7L) and percentage of Al2O3 particles (1-5%). It was found that the effect of adding nanoparticles on heat transfer is limited for small size'hot block and low Richardson number and becomes important for higher values of Lh and Ri. The thermal entropy generation increases by increasing the concentration of nanoparticles for all Richardson numbers, but the variation viscous entropy generation with concentrations depends on Ri values. (C) 2017 Elsevier Ltd. All rights reserved.