Abstract
•The natural convection is enhanced as Ra increases which leads to increase the average Nu while the average Sh decreases.•The increase in Da increases the fluid activity, thermal boundary layers, average Nu and Sh.•The streamlines, isotherms and isoconcentration are insensitive for the Lewis number and Brownian motion parameter.•A monolithic finite element multigrid approach is utilized.
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In this paper, a numerical study is performed for the steady natural convection inside an open enclosure filled with a porous medium using nanofluid. The two phase model is applied for the nanofluid and the Darcy number for the porous medium. The governing partial differential equations are solved numerically using the Galerkin finite element method with Q2/P1disc element and valuable comparisons are performed. The computations are produced for wide ranges of the governing parameters, i.e. Rayleigh number Ra from 104 to 107, Darcy number Da from 10−2 to 10−6, Lewis number L from 0.1 to 1, buoyancy ratio Nr from 0.1 to 1 and Nb from 0.1 to 1. It is found that the average heat transfer rate is a decreasing function of the Lewis number and the buoyancy ratio for high values of Rayleigh number.