Three dimensional simulation of natural convection and entropy generation in an air and MWCNT/water nanofluid filled cuboid as two immiscible fluids with emphasis on the nanofluid height ratio's effects

摘要

This paper reports a numerical study of the natural convection and entropy generation for a layered fluid system in a cuboid enclosure which is differentially heated from sides and filled by two immiscible gas/liquid fluids (air and MWCNTs-water nanofluid). This study emphasize on the effects of the liquid interface aspect ratio, solid volume fraction of nanofluid, and Rayleigh number on the fluid flow, heat transfer and entropy generation. The fluid flow streamlines, contours of local fluid friction irreversibility, temperature, and local heat transfer irreversibility in the 3D enclosure are obtained. The local and averaged Nusselt number and volumetric entropy generation are also discussed. The results show that the nanofluid interface aspect ratio has significant influences on the fluid flow, heat transfer performance and entropy generation. Moreover, it is shown that the total entropy generation and mean Nusselt number are reduced by increasing of nanofluid interface aspect ratio and are enhanced by increasing of Rayleigh,number. (C) 2016 Elsevier B.V. All rights reserved.