Comparison of Natural Convection Around a Circular Cylinder With Different Geometries of Cylinders Inside a Square Enclosure Filled With Ag-Nanofluid Superposed Porous-Nanofluid Layers

Abstract

Numerical simulations are carried out for fluid flow and natural convection heat transfer induced by a temperature difference between a hot inner cylinder with different geometries (i.e., circular; triangular; elliptic; rectangular; and rhombic) and a cold outer square enclosure filled with nanofluid superposed porous-nanofluid layers. The Darcy–Brinkman model is applied for the saturated porous layer with nanofluid. Moreover, the transport equations (mass, momentum, and energy) are solved numerically using the Galerkin weighted residual method by dividing the domain into two sets of equations for every layer with incorporating a nonuniform mesh size. The considered domains in this investigation are closely examined over a wide range of Rayleigh number (103 ≤ Ra ≤ 106), Darcy number (10−5 ≤ Da ≤ 10−1), the thickness of porous layer (0% ≤ Xp ≤ 100%), thermal conductivity ratio (1 ≤ Rk ≤ 20), and nanoparticle volume fraction (0 ≤ φ ≤ 0.1), respectively. The nanofluid is considered to be composed of Ag-nanoparticle and water as a base fluid. The results showed that the obtained total surfaces-averaged Nusselt numbers of the enclosure, in all cases, at the same operating conditions, the rate of heat transfer from the outer enclosure which the triangular cylinder is located inside is better. Also, as the thickness of the porous layer is increased from 20% to 80%, the free convection performance will decrease significantly (to about 50%) due to the hydrodynamic properties of the porous material.

Computational Fluid Dynamics Investigation of Buoyancy Driven Flow Between Circular Body and Wavy Enclosure Filled with Nanofluid/Porous Medium

“…This method has been simplified for coupling of the momentum equation between nano-fluid domain and porous domain. The governing equations for the nano-fluid domain in the dimensional form are [54,61] The physical characteristics of the nanofluid could be expressed as follows:…”

“…They have concluded that average Nusselt number decreases with the increase of the Reynolds number and corrugations number. Recently, Hussain and Rahomey [54] studied the natural convection between various internal cylinder bodies like circular, square, triangular and elliptical placed within a square enclosure filling by nanofluid and porous media saturated by the same nano-fluid. Results have shown that is better in heat transfer rate.…”

Conjugate Natural Convection in a Square Porous Cavity Filled with a Nanofluid in the Presence of Two Isothermal Cylindrical Sources

“…In all cases, an increment in Rayleigh and Darcy numbers expand the heat transfer and average Nusselt number. Also, Hussain and Rahomey [10] has been showed the efficiency of difference geometries inside a square porous cavity. The effect of magnetohydrodynamic natural convection in a nanofluid-porous annulus area has been studied by Sheikholeslami and Shehzad [11], Sheikholeslami et al, [12] and Ahmed et al, [13].…”

“…We can cite a review of Khanafer et al, [1] and Kasaeian et al, [2]. Many theoretical and experimental investigations have been realized in this domain, we quote about that Sheikhzadeh and Nazari [4] have studied the steady state natural convection in porous medium saturated with (Al2O3-Water) inside differentially heated square cavity [3][4][5][6][7][8][9][10][11][12][13][14][15]. The governing equations have solved by finite volume approach using SIMPLER algorithm.…”

“…Those considered the effect of Rayleigh number, Lewis number and the dimensionless ratio between the thermophoretic and Brownian coefficients on the thermal heat transfer. Dogonchi et al, [9] and Hussain and Rahomey [10] have presented a numerical analysis of free convection in a nanofluid-saturated porous annulus developed with different geometries (circular; triangular; elliptic; rectangular; rhombic and square). The governing equations have solved by finite element method.…”