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

Tarikul Islam,Md Fayz-Al-Asad,Nazma Parveen,Mehmet Yavuz

doi:10.3390/fractalfract6020101

Abstract

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.

Highlights

The heat transfer in a square enclosure is analyzed in the present study to visualize the heat flow and find an efficient way of transferring heat in the chamber under the influence of the periodic MHD
More than six types of nanofluids have been used to examine the best performance of enhancing temperature transport compared to the base fluid
The value of the Prandtl number (Pr = 6.8377) is constant for copper-water nanofluid and it is varied with other nanofluids

Summary

Introduction

Nanofluids are a novel fluid class with a higher thermal conductivity than conventional fluids. Nanofluids are formed by using nanoparticles with a size of 1–100 nm, which are made from different materials and base fluids, for example, Au, Ag, Cu, SiC, TiC, CuO, Al2 O3 , SiN, TiO2 , pump oil, ethylene glycol, water, engine oil, glycerol, etc. Choi [1,2] first introduced this new novel class of fluids. Different researchers [3,4,5,6,7] investigated the convective heat transfer of different nanofluids with different conditions and its various applications. Khan et al [8] investigated numerical investigation of second order velocity flow of micropolar ferrofluid inside a permeable medium. Khan et al [9]

Objectives

Methods

Results

Conclusion