Natural convective heat transfer through two entrapped triangular cavities filled with a nanofluid: Buongiorno's mathematical model

Free convection of water based nanofluid inside two entrapped triangular cavities under the effects of Brownian diffusion and thermophoresis is numerically studied. The bottom and upper walls of the cavities are kept at high constant temperature while the rest walls are kept at low constant temperature. Dimensionless governing equations formulated using stream function, vorticity, temperature and nanoparticles volume fraction have been solved by finite difference method of the second order accuracy. The effects of the Rayleigh number, Lewis number and buoyancy-ratio parameter on fluid flow, heat and mass transfer have been analyzed. It has been found that, taking into account the used temperature boundary conditions, the bottom triangular cavity is more sensitive to changes of the Rayleigh number and buoyancy-ratio parameter, while the upper cavity is not so sensitive to changes of these parameters. In addition, an increase in the Rayleigh number and buoyancy-ratio parameter reflects non-uniform distributions of nanoparticles inside cavities. (C) 2017 Elsevier Ltd. All rights reserved.