Mixed convection heat transfer in a square porous cavity filled with a nanofluid with suction/injection effect

Mixed convection in a square porous cavity filled with a water-based nanofluid under the effects of suction/injection zones, Brownian diffusion and thermophoresis is studied. The nanofluid flow of high concentration penetrates into the cavity through the bottom open border and exits from the cavity through the upper open part. High nanofluid concentration, low temperature and constant vertical velocity at the bottom open zone of the cavity is applied, whereas the outflow boundary conditions are subjected to the open upper border. Vertical walls are assumed to be isothermal and horizontal ones are adiabatic. The zero nanoparticles mass flux is considered for all rigid walls. The Buongiorno nanofluid model and Darcy approach are applied for numerical description of the considered process inside the porous medium. The formulated boundary-value problem is solved using the finite difference method. The effects of the Rayleigh number, Darcy number, Reynolds number and sizes of the input and output sections on nanofluid flow and heat transfer are studied. It has been found the heat transfer enhancement with the modified Rayleigh number, Reynolds number and sizes of the inlet/outlet sections. (C) 2018 Elsevier Ltd. All rights reserved.