Natural convection heat transfer in an inclined square enclosure filled with a porous medium saturated by nanofluid using Buongiorno's mathematical model

•Free convection of nanofluid in a titled porous cavity is studied.•Two phase Buongiorno model is used for simulation.•Thickness of mass boundary layer reduces by decreasing porosity.•Thickness of mass boundary layer reduces by increasing Rayleigh number.•Cu nanoparticles show more uniform distribution than Al2O3 ones.

This paper presents numerical study of nanofluid free convection in a porous enclosure. Two vertical walls are maintained at constant but different temperatures. (Th > Tc), while the remaining walls are insulated Two-phase Buongiorno nanofluid model is employed in this work considering Brownian diffusion and thermophoresis effects. Governing equations are solved using a Simple-based finite volume method. Two different nanofluids are considered in this study, i.e. Al2O3/water and Cu/water. Numerical simulations are conducted for different porous Rayleigh numbers (Rap = 102, 103 and 104), porosities (ɛ = 0.5, 0.7 and 0.9), particle volume fractions (0⩽φAve⩽0.04) and inclination angle of enclosure ranging from 0° to 60°. Numerical results indicate that porosity plays an important role on the heat transfer rate especially at high porous Rayleigh numbers. Compared to Al2O3, Cu nanoparticles show more uniform distribution inside the enclosure. Numerical results demonstrate that there is mass boundary layer adjacent to enclosure walls and its thickness decreases by reducing porosity or increasing porous Rayleigh number.

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