scholarly journals Influence of magnetohydrodynamic viscous flow on entropy generation within porous micro duct using the Lattice Boltzmann Method

RSC Advances ◽  
2017 ◽  
Vol 7 (49) ◽  
pp. 30673-30686
Author(s):  
Raja Rabhi ◽  
Abir Yahya ◽  
Bayssain Amami ◽  
Hacen Dhahri

In this work entropy generation and heat transfer for magnetohydrodynamic (MHD) forced convection flow in a micro duct filled with a porous medium are investigated using a modified axisymmetric Lattice Boltzmann Method.

2019 ◽  
Vol 29 (12) ◽  
pp. 4746-4763 ◽  
Author(s):  
Qingang Xiong ◽  
Arash Khosravi ◽  
Narjes Nabipour ◽  
Mohammad Hossein Doranehgard ◽  
Aida Sabaghmoghadam ◽  
...  

Purpose This paper aims to numerically investigate the nanofluid flow, heat transfer and entropy generation during natural convection in an annulus. Design/methodology/approach The lattice Boltzmann method is used to simulate the velocity and temperature fields. Furthermore, some special modifications are applied to make the lattice Boltzmann method capable for simulation in the curved boundary conditions. The annulus is filled with CuO-water nanofluid. The dynamic viscosity of nanofluid is estimated using KLL (Koo-Kleinstreuer-Li) model, and the nanoparticle shape effect is taken account in calculating the thermal conductivity. On the other hand, the local/volumetric entropy generation is used to show the irreversibility under influence of different parameters. Findings The effect of considered governing parameters including Rayleigh number (103<Ra < 106); nanoparticle concentration (0<<0.04) and configuration of annulus on the flow structure; temperature field; and local and total entropy generation and heat transfer rate are presented. Originality/value The originality of this work is using of lattice Boltzmann method is simulation of natural convection in a curved configuration and using of Koo–Kleinstreuer–Li correlation for simulation of nanofluid.


Author(s):  
HamidReza KhakRah ◽  
Payam Hooshmand ◽  
David Ross ◽  
Meysam Jamshidian

Purpose The purpose of this paper is to investigate the compact finite-difference lattice Boltzmann method is used to simulate the free convection within a cavity. Design/methodology/approach The finite-difference discretization method enables the numerical simulations to be run when there are non-uniform and curvilinear grids with a finer near-wall grid resolution. Furthermore, the high-order method is applied in the numerical approach, which makes it possible to go with relatively coarse mesh in respect to simulations, which used classical lattice Boltzmann method. The configuration of the cavity is set to sine-walled square. In addition, the cavity is filled with Al2O3-water nanofluid, and the Koo–Kleinstreuer–Li model is used to estimate the properties of nanofluid. Findings The nanoparticle (Al2O3) concentration in the base fluid (water) is considered in a range of 0-0.04. The nanofluid flow and heat transfer are investigated in laminar regime with Rayleigh number in the range of 103-106. The second law analysis is used to study the effects of different governing parameters on the local and volumetric entropy generation. The Rayleigh number, configuration of the cavity and nanoparticle concentration are considered as the governing parameters. The results are mainly focused on the flow structure, temperature field, local and volumetric entropy generation and heat transfer performance. Originality/value The originality of this study is using of a modern numerical method supported by an accurate prediction for nanofluid properties to simulate the flow and heat transfer during natural convection in a cavity.


2020 ◽  
pp. 96-96
Author(s):  
Abchouyeh Asadi ◽  
Ganaoui El ◽  
Rasul Mohebbi ◽  
Mohammad Zarrabi ◽  
Omid Fard ◽  
...  

In this study, the Lattice Boltzmann Method (LBM) is employed in order to examine the fluid flow and forced convection heat transfer inside a two-dimensional horizontal channel with and without obstacles. In order to enhance the heat and thermal energy transfer within the channel, different obstacle arrangements are posed to the flow field and heat transfer with the purpose of studying their sensitivity to these changes. The results indicate that, when the value of the Reynolds number is maximum, the maximum average Nusselt numbers happens on the lower wall (Case 4). The paper extends the topic to the use of nanofluids to introduce a possibility to enhancement of the heat transfer in the channel with an array of the obstacles with forced convection. For this purpose, the AgMgO/water micropolar hybrid nanofluid is used, and the volume fraction of the nanoparticle (50% Ag and 50% MgO by volume) is set between 0 and 0.02. The results showed that, when the hybrid nanofluid is used instead of a typical nanofluid, the rate of the heat transfer inside the channel increases, especially for the high values of the Reynolds number, and the volume fraction of the nanoparticles. Increasing the volume fraction of the nanoparticles increase the local Nusselt number ( 1.17-fold). It is shown that the type of obstacle arrangement and the specific nanofluid can exerts significant effects on the characteristics of the flow field and heat transfer in the channel. This study provides a platform for using the LBM to examine fluid flow through discrete obstacles in offset positions.


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