Nanofluids In Square Enclosure Research Articles

Impact of Non-Uniform Periodic Magnetic Field on Unsteady Natural Convection Flow of Nanofluids in Square Enclosure

In this article, unsteady free convective heat transport of copper-water nanofluid within a square-shaped enclosure with the dominance of non-uniform horizontal periodic magnetic effect is investigated numerically. Various nanofluids are also used to investigate temperature performance. The Brownian movement of nano-sized particles is included in the present model. A sinusoidal function of the y coordinate is considered for the magnetic effect, which works as a non-uniform magnetic field. The left sidewall is warmed at a higher heat, whereas the right sidewall is cooled at a lower heat. The upper and bottom walls are insulated. For solving the governing non-linear partial differential equation, Galerkin weighted residual finite element method is devoted. Comparisons are made with previously published articles, and we found there to be excellent compliance. The influence of various physical parameters, namely, the volume fraction of nanoparticles, period of the non-uniform magnetic field, Rayleigh number, the shape and diameter of nanoparticles, and Hartmann number on the temperature transport and fluid flow are researched. The local and average Nusselt number is also calculated to investigate the impact of different parameters on the flow field. The results show the best performance of heat transport for the Fe3O4-water nanofluid than for other types of nanofluids. The heat transport rate increases 20.14% for Fe3O4-water nanofluid and 8.94% for TiO2-water nanofluid with 1% nanoparticles volume. The heat transportation rate enhances with additional nanoparticles into the base fluid whereas it decreases with the increase of Hartmann number and diameter of particles. A comparison study of uniform and non-uniform magnetic effects is performed, and a higher heat transfer rate is observed for a non-uniform magnetic effect compared to a uniform magnetic effect. Moreover, periods of magnetic effect and a nanoparticle’s Brownian movement significantly impacts the temperature transport and fluid flow. The solution reaches unsteady state to steady state within a very short time.

Numerical analysis of Al2O3/water nano-fluids natural convection and entropy generation in enclosures

The aim of this work is to analyze the natural convection phenomena and entropy generation of water-based Al 2 O 3 nanofluids in square enclosure. The simulated domain corresponds to a square cavity heated from below and cooled from the top. The left and right walls are heated up to a height H = (3/4 W) and are adiabatic in the remaining part (1- H ). Numerical investigations have been carried out based on coupled partial differential equations of momentum and energy which are solved using finite volume method. The effective thermal conductivity of the nanofluid was expressed by the Maxwell-Garnetts model however the dynamic viscosity was calculated according to the Brinkman formula. The obtained results were presented by average Nusselt number, streamlines, isotherms and entropy generation with various pertinent parameters, namely, Rayleigh number (10 0 ≤ Ra ≤ 10 6 ), volumetric fraction of nanoparticles (1% ≤ ϕ ≤ 4% ). It was found that the heat transfer increases with the increase of Rayleigh number and volume fraction. The choice of these parameters is important to obtain maximum enhancement of heat transfer with minimum entropy generation.

Nanofluid in tilted cavity with partially heated walls

Lattice Boltzmann Method is applied to investigate the natural convection flow utilizing nanofluids in square enclosure with partially heated walls. The fluid in the cavity is a water-based nanofluid containing different types of nanoparticles: copper (Cu), silver (Ag), alumina (Al2O3) and titania (TiO2). The effective thermal conductivity and viscosity of nanofluid are calculated by the Maxwell–Garnetts (MG) and Brinkman models, respectively. This investigation was compared with other numerical methods and found to be in excellent agreement. Numerical results for the flow and heat transfer characteristics are obtained for various values of the nanoparticle volume fraction, Rayleigh numbers and inclination angles together with different kinds of nanofluids. The type of nanofluid is a key factor for heat transfer enhancement. Choosing copper as the nanoparticle proved to have the highest cooling performance for this problem. It is also shown that the Nusselt number is an increasing function of each of the nanoparticle volume fraction and Rayleigh numbers.

Mixed convection of water-based nanofluids in a square enclosure heated and cooled on adjacent walls

This study examines the mixed convection of water-based nanofluids in a lid-driven square enclosure heated from one side and cooled from the stationary adjacent side while the other sides are kept stationary and adiabatic. The conservation equations are solved numerically for the stream function, vorticity, and temperature using the differential quadrature method. The Grashof number is kept at a constant value of 10 4 in the present study, and the Reynolds number is varied so that the Richardson number will have values in the range of 0.1 to 10. Nanoparticles volume fraction φ is varied as 0%, 5% and 10% and the value of η the ratio of the nanolayer thickness to the original particle radius, is fixed to 0.1. The results show that the motion of the side wall and nanoparticle usage has significant effects on the flow and temperature fields. A significant increase in the average Nusselt number is seen with an increase in the volume fraction of nanoparticles and a decrease in the Richardson number.

Lattice Boltzmann simulation of natural convection heat transfer of Al 2O 3/water nanofluids in a square enclosure

In the present study, mathematical modeling is performed to simulate natural convection of Al 2O 3/water nanofluids in a vertical square enclosure using the lattice Boltzmann method (LBM). Results indicate that the average Nusselt number increases with the increase of Rayleigh number and particle volume concentration. The average Nusselt number with the use of nanofluid is higher than the use of water under the same Rayleigh number. However, the heat transfer rate of the nanofluid takes on a lower value than water at a fixed temperature difference across the enclosure mainly due to the significant enhancement of dynamic viscosity. Furthermore, great deviations of computed Nusselt numbers using different models associated with the physical properties of a nanofluid are revealed. The present results are well validated with the works available in the literature and consequently LBM is robust and promising for practical applications.