Natural convection flow of a hybrid nanofluid in a square enclosure partially filled with a porous medium using a thermal non-equilibrium model

Buoyancy driven flow inside a superposed enclosure filled with composite porous hybrid nanofluid layers was investigated numerically using a local thermal nonequilibriurn model for the heat transfer between the fluid and the solid phases. The bottom wall of the enclosure was partly heated to provide a heat flux, while the other parts of the wall were thermally insulated. The top and vertical walls of the enclosure were maintained at constant cold temperatures. The Darcy-Brinkman model was adopted to model the flow inside the porous layer. The Galerkin finite element method was used to solve the governing equations using the semi-implicit method for pressure linked equations algorithm. The selected parameters are presented for the Rayleigh number (Rn), 10 <= Ril 107, the Darcy number (Da), 10-7 < Da 1, the porous layer thickness (5), 0 <= S 1, the modified conductivity ratio (y), 10(-1) <= Da <= 10(4), the interphase heat transfer coefficient (H), 10-1t H i 1000, the heat source length (B), 0.2, 0.4, 0.6, 0.8 and 1, and the nanoparticle volume fraction (q), 0 (-) 0.2. It has been concluded that the rate of heat transfer of hybrid nanofluid (Cu A1203/water) is higher than with the pure fluid. Furthermore, at Ra <= 10, the heat transfer rate maintains its maximum value when S reaches the critical value (S = 0:3). The values of S, Da, and B were found to have a significant effect on the heat removal from the heat source. Increasing the values of y and H can strongly enhance the heat transfer rate and satisfy the thermal equilibrium case. Published under license by AP Publishing.