Effect on Natural Convection Heat Transfer of Nanofluid in an Enclosure Due to Uncertainties of Viscosity and Thermal Conductivity

Abstract

In this study we aim to identify effects due to uncertainties in effective dynamic viscosity and thermal conductivity of nanofluid on laminar natural convection heat transfer in a square enclosure. Numerical simulations have been undertaken incorporating a homogeneous solid-liquid mixture formulation for the two-dimensional buoyancy-driven convection in the enclosure filled with alumina-water nanofluid. Two different formulas from the literature are each considered for the effective viscosity and thermal conductivity of the nanofluid. Simulations have been carried out for the pertinent parameters in the following ranges: the Rayleigh number, Raf = 103 ∼ 106 and the volumetric fraction of alumina nanoparticles, φ = 0 ∼ 4%. Significant difference in the effective dynamic viscosity enhancement of the nanofluid calculated from the two adopted formulas, other than that in the thermal conductivity enhancement, was found to play as a major factor, thereby leading to contradictory results concerning the heat transfer efficacy of using nanofluid in the enclosure.

Similarity solutions to viscous flow and heat transfer of nanofluid over nonlinearly stretching sheet

“…The reported breakthrough in substantially increasing the thermal conductivity of fluids by adding very small amounts of suspended metallic or metallic oxide nanoparticles (Cu, CuO, Al 2 O 3 ) to the fluid [1][2] , or alternatively using nanotube suspensions [3][4] conflicts with the classical theories [5][6][7][8][9][10][11][12][13] , of estimating the effective thermal conductivity of suspensions. There have been published several recent numerical studies on the modeling of natural convection heat transfer in nanofluids, Congedo et al [14] , Ghasemi and Aminossadati [15] , Ho et al [16][17] , and several others. These studies used traditional finite difference and finite volume techniques with the tremendous call on computational resources that these techniques necessitate.…”

Unsteady MHD free convection flow past a vertical permeable flat plate in a rotating frame of reference with constant heat source in a nanofluid

“…The comprehensive references on nanofluid can be found in the recent book by Das et al [12] and in the review papers by Trisaksri and Wongwises [35], Wang and Mujumdar [37], and Kakaç and Pramuanjaroenkij [23]. There have been published quite many numerical studies on the modeling of natural convection heat transfer in nanofluids, namely Khanafer et al [25], Roy et al [34], Jou and Tzeng [22], Ho et al [18,19], Congedo et al [11], and Ghasemi and Aminossadati [15]. These studies have used traditional finitedifference and finite-volume techniques with the tremendous call on computational resources that these techniques necessitate.…”

Radiative Heat Transfer on Nanofluids Flow Over a Porous Convective Surface in the Presence of Magnetic Field

“…Metal, metal oxides, ceramics and nonmetals such as carbon nanotubes and graphene can be used as nanoparticles in nanofluids, whereas water, ethylene glycol, oil and polymer solutions are generally used as base fluids. Several studies on nanofluids have been conducted by a number of researchers with respect to thermal conductivity enhancement and viscosity [2][3][4][5], phase change heat transfer [6][7][8][9] and convective heat transfer [10][11][12][13].Ghasemi and Aminossadati [14], Congedo et al [15] and Ho et al [16] and [17] presented some numerical studies on the modeling of natural convection heat transfer in nanofluids using finite volume techniques or traditional finite difference methods.Magnetic nanofluid is a unique material that has both the liquid and magnetic properties. Many of the physical properties of these fluids can be tuned by varying magnetic field.…”