The effect of inclination angle and hot wall configuration on Cu-water nanofluid natural convection inside a porous square cavity

Natural Convection of Cu-water nanofluid in an inclined cavity filled with porous media has been investigated using two-phase mixture model. The co-effect of cavity's inclination angle, heater configuration, use of nanofluid and porous media on heat transfer enhancement has been studied with detailed investigation of the decision variables effect (Rayleigh number, Darcy number, inclination angle, and volume fraction of Cu nanoparticles) on heat transfer characteristics. The investigation considers the laminar flow for natural convection (10(4) <= Ra <= 10(6)). Darcy-Brinckman-Forchheimer model has been used as for the simulation of porous media and two-phase mixture model has been applied to model the behavior of nanofluid. In accordance it has been shown that simultaneous use of nanofluid with porous media in weak convection flows is beneficial, but for strong natural convection fields that would be unfavorable and decreases heat transfer rate. It has been concluded that the effect of inclination angle highly depends on the hot wall location as in some states having the square cavity inclined would be of benefit while in another case the total heat transfer would decline. The results show that proper selection of heater configuration (side wall or corner heating) and inclination angle inline with nanofluid concentration and porous media properties can highly affect heat transfer performance. Furthermore, optimal solutions might exist for different conditions. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.