Numerical simulation of natural convection in a square enclosure filled with nanofluid using the two-phase Lattice Boltzmann method
Cong Qi
0
Yurong He
0
Shengnan Yan
0
Fenglin Tian
0
Yanwei Hu
0
0
School of Energy Science and Engineering, Harbin Institute of Technology
, Harbin, 150001,
China
Considering interaction forces (gravity and buoyancy force, drag force, interaction potential force, and Brownian force) between nanoparticles and a base fluid, a two-phase Lattice Boltzmann model for natural convection of nanofluid is developed in this work. It is applied to investigate the natural convection in a square enclosure (the left wall is kept at a high constant temperature (TH), and the top wall is kept at a low constant temperature (TC)) filled with Al2O3/H2O nanofluid. This model is validated by comparing numerical results with published results, and a satisfactory agreement is shown between them. The effects of different nanoparticle fractions and Rayleigh numbers on natural convection heat transfer of nanofluid are investigated. It is found that the average Nusselt number of the enclosure increases with increasing nanoparticle volume fraction and increases more rapidly at a high Rayleigh number. Also, the effects of forces on nanoparticle volume fraction distribution in the square enclosure are studied in this paper. It is found that the driving force of the temperature difference has the biggest effect on nanoparticle volume fraction distribution. In addition, the effects of interaction forces on flow and heat transfer are investigated. It is found that Brownian force, interaction potential force, and gravity-buoyancy force have positive effects on the enhancement of natural convective heat transfer, while drag force has a negative effect.
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Background
Compared with common fluids such as water, nanofluid,
using nanoscale particles dispersed in a base fluid, has
an effect of enhancing the performance of natural
convection heat transfer due to its high heat conductivity
coefficient. Many researchers investigated nanoparticles
and nanofluid in recent years. Wang et al. [1]
synthesized stimuli-responsive magnetic nanoparticles and
investigated the effect of nanoparticle fraction on its
cleavage efficiency. Bora and Deb [2] developed a novel
bioconjugate of stearic acid-capped maghemite
nanoparticle (-Fe2O3) with bovine serum albumin. Guo et al.
[3] produced magnetic nanofluids containing -Fe2O3
nanoparticles using a two-step method, measured their
thermal conductivities and viscosity, and tested their
convective heat transfer coefficients. Pinilla et al. [4]
investigated the growth of Cu nanoparticles in a
plasmaenhanced sputtering gas aggregation-type growth region.
Yang and Liu [5] produced a kind of stable nanofluid by
surface functionalization of silica nanoparticles. Zhu
et al. [6] developed a wet chemical method to produce
stable CuO nanofluids. Nadeem and Lee [7] investigated
the steady boundary layer flow of nanofluid over an
exponential stretching surface. Wang and Fan [8] reviewed
the nanofluid research in the last 10 years.
Natural convection is applied in many fields, and
extensive researches have been performed. Oztop et al. [9]
and Ho et al. [10] respectively investigated natural
convection in partially heated rectangular enclosures and
discussed the effects of viscosity and thermal
conductivity of nanofluid on laminar natural convection heat
transfer in a square enclosure by a finite-volume method.
Saleh et al. [11] investigated heat transfer enhancement
utilizing nanofluids in a trapezoidal enclosure by a finite
difference approach. Ghasemi et al. [12], Santra et al. [13],
and Aminossadati et al. [14] numerically simulated natural
convection in a triangular enclosure and studied the
behavior of natural convection heat transfer in a
differentially heated square cavity, described a study on natural
convection of a heat source embedded in the bottom
wall of an enclosure, and used the SIMPLE algorithm
to solve the governing equation. Kargar et al. [15] used
computational fluid dynamics and an artificial neural
network to investigate the cooling performance of two
electronic components in an enclosure. Abu-Nada et al.
[16] investigated the effect of variable properties on
natural convection in enclosures filled with nanofluid,
and the governing equations are solved by an efficient
finite-volume method. Hwang et al. [17] investigated
the thermal characteristics of natural convection in a
rectangular cavity heated from below by Jang and Choi's
model [18].
The Lattice Boltzmann method is a new way to
investigate natural convection. Compared with the
above traditional methods, the Lattice Boltzmann
method has many merits including that boundary
conditions can be conveniently dealt with, the
transform between macroscopic and microscopic equations
is easily achieved, the details of the fluid can be
presented, and so on. In addition, nanofluid as the
media can enhance heat transfer due to factors such
as nanofluids having higher thermal conductivity and
the nanoparticles in the fluid disturbing the laminar
flow. Therefore, ma (...truncated)