scholarly journals Numerical Simulation of Free Convection in a Three-Dimensional Enclosure Full of Nanofluid with the Existence a Magnetic Field

2020 ◽  
Vol 22 (6) ◽  
pp. 405-411
Author(s):  
Said Bouchta ◽  
M’barek Feddaoui
Keyword(s):  
Magnetic Field ◽  
Free Convection ◽  
Thermal Field ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Nusselt Numbers ◽  
Simplec Algorithm ◽  
Nanometric Particles ◽  
Left And Right ◽  
Volume Method

A numerical analysis was performed to study the influence of a magnetic field in free convection in a cube full with nanofluid. To solve the equation, we appeal to finite volume method. The SIMPLEC algorithm is used for pressure-velocity coupling. All walls are adiabatic, except for the left and right walls that are heated differently. The effects of the Rayleigh and Hartmann numbers, as well as the volume fraction of nanometric particles were studied. Results are conveyed in the form of isotherms, streamlines, velocity curves and Nusselt numbers. It has been shown that as the percentage of nanoparticles increases and the number of Rayleigh increases, heat transfer improves. Hartman number has considerable influence on hydrodynamic and thermal field.

scholarly journals Numerical Simulation of Free Convection in a Partially Heated Three-Dimensional Enclosure Filled with Ionanofluid ([C4mim][NTf2]-Cu)

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Said Bouchta ◽  
M’barek Feddaoui ◽  
Abdellatif Dayf
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Free Convection ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Three Dimensional ◽  
Particle Volume ◽  
Simplec Algorithm ◽  
Current Lines ◽  
Volume Method

A numerical analysis was performed to study free convection in a stationary laminar regime in a partially heated cube filled with ionanofluid. To numerically solve the dimensionless equations, we applied the finite volume method using the SIMPLEC algorithm for pressure correction. All walls are adiabatic, except for the left and right side walls which are partially heated differently. At the end of this simulation, several results are given in the form of current lines, isotherms, and variations in the Nusselt number. These results are obtained by analyzing the effect of a set of factors such as Rayleigh number, particle volume fraction, cold and source position on the dynamic and thermal fields, and heat transfer. It has been shown that the percentage of nanoparticles and high Rayleigh numbers significantly increase heat transfer by ionanofluid. Two comparisons have been made, between ionic fluid and ionanofluid at isotherms and streamlines, and between nanofluid and ionanofluid at Nusselt number, which show the advantage of using ionanofluid in heat transfer.

MHD natural convection of Cu/H2O nanofluid in a horizontal semi-cylinder with a local triangular heater

2018 ◽  
Vol 28 (12) ◽  
pp. 2979-2996 ◽  
Author(s):  
A.S. Dogonchi ◽  
Mikhail A. Sheremet ◽  
Ioan Pop ◽  
D.D. Ganji
Keyword(s):  
Magnetic Field ◽  
Rayleigh Number ◽  
Free Convection ◽  
Shape Factor ◽  
Uniform Magnetic Field ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Horizontal Cylinder ◽  
Content Type ◽  
Nanoparticles Volume Fraction

Purpose The purpose of this study is to investigate free convection of copper-water nanofluid in an upper half of circular horizontal cylinder with a local triangular heater under the effects of uniform magnetic field and cold cylinder shell using control volume finite element method (CVFEM). Design/methodology/approach Governing equations formulated in dimensionless stream function, vorticity and temperature variables using the single-phase nanofluid model with Brinkman correlation for the effective dynamic viscosity and Hamilton and Crosser model for the effective thermal conductivity have been solved numerically by CVFEM. Findings The impacts of control parameters such as the Rayleigh number, Hartmann number, nanoparticles volume fraction, local triangular heater size, shape factor on streamlines and isotherms as well as local and average Nusselt numbers have been examined. The outcomes indicate that the average Nusselt number is an increasing function of the Rayleigh number, shape factor and nanoparticles volume fraction, while it is a decreasing function of the Hartmann number. Originality/value A complete study of the free convection of copper-water nanofluid in an upper half of circular horizontal cylinder with a local triangular heater under the effects of uniform magnetic field and cold cylinder shell using CVFEM is addressed.

Effect of Periodic Imposed Heat Flux on Three-Dimensional Natural Convection in a Partially Heated Cubical Enclosure

2016 ◽  
Vol 831 ◽  
pp. 83-91
Author(s):  
Lahoucine Belarche ◽  
Btissam Abourida
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Study ◽  
Control Volume ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Cubical Enclosure ◽  
Simplec Algorithm ◽  
Volume Method

The three-dimensional numerical study of natural convection in a cubical enclosure, discretely heated, was carried out in this study. Two heating square sections, similar to the integrated electronic components, are placed on the vertical wall of the enclosure. The imposed heating fluxes vary sinusoidally with time, in phase and in opposition of phase. The temperature of the opposite vertical wall is maintained at a cold uniform temperature and the other walls are adiabatic. The governing equations are solved using Control volume method by SIMPLEC algorithm. The sections dimension ε = D / H and the Rayleigh number Ra were fixed respectively at 0,35 and 106. The average heat transfer and the maximum temperature on the active portions will be examined for a given set of the governing parameters, namely the amplitude of the variable temperatures a and their period τp. The obtained results show significant changes in terms of heat transfer, by proper choice of the heating mode and the governing parameters.

scholarly journals Natural Convection of Dusty Hybrid Nanofluids in an Enclosure Including Two Oriented Heated Fins

2019 ◽  
Vol 9 (13) ◽  
pp. 2673 ◽  
Author(s):  
Raizah
Keyword(s):  
Natural Convection ◽  
Volume Fraction ◽  
Simple Algorithm ◽  
Systems Of Equations ◽  
Nusselt Numbers ◽  
Pressure Distributions ◽  
Nanoparticles Volume Fraction ◽  
Hybrid Nanofluids ◽  
Volume Method ◽  
Present Simulation

In the current work, the natural convection of dusty hybrid nanofluids in an enclosure including two inclined heated fins has been studied via mathematical simulation. The inclined heated fins are arranged near to the enclosure center with variations on their orientations and lengths. The present simulation is represented by two systems of equations for the hybrid nanofluids that are dusty. The pressure distributions for the dusty phase and hybrid nanofluids phase are evaluated using a SIMPLE algorithm based on the finite volume method. The numerical results are examined using contours of the streamlines, isotherms for the hybrid nanofluids and velocity components for the dusty phase. In addition, the graphical illustrations for profiles of the local and average Nusselt numbers are presented. The main results reveal that an increase in the mixture densities ratio and dusty parameter reduces the rate of the heat transfer. Both the local and average Nusselt numbers are supported as the fins lengths increase regardless of the fins’ rotation. In addition, the nanoparticles volume fraction enhances the thermal boundary layer near the top wall.

scholarly journals Three-dimensional numerical study of mixed convection within a ventilated cavity (Shape ‘ L ‘) crossed by a nanofluid under the effect of a magnetic field

2020 ◽  
Vol 307 ◽  
pp. 01027
Author(s):  
S. KHERROUBI ◽  
K. RAGUI ◽  
N. LABSI ◽  
Y.K. BENKAHLA ◽  
A. BOUTRA
Keyword(s):  
Magnetic Field ◽  
Mixed Convection ◽  
Volume Fraction ◽  
Numerical Study ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Left Wall ◽  
Ventilated Cavity ◽  
The Right

The present work is dedicated to the three-dimensional numerical study of mixed convection heat transfer, taking place within a ventilated cavity (of shape L) crossed by Cu-water nanofluid. The enclosure is subjected to the action of a magnetic field. The ventilation is assured by two openings of the same size. The cold flow enters by an opening practiced at the top of the left wall, and exits by another opening practiced at the bottom of the right vertical wall. All the cavity walls are maintained at the same temperature, superior to that of the entering flow, except the side walls which are considered as adiabatic. The control parameters are: the Reynolds number and the Hartmann number as well as the nanoparticles volume fraction.

Numerical Investigations About the Effect of Non-Condensable Gas on Cavitating Flows

2009 ◽  
Author(s):  
Hamed Sadeghi ◽  
Masoud Darbandi
Keyword(s):  
Turbulent Flows ◽  
Volume Fraction ◽  
Working Fluid ◽  
Numerical Investigations ◽  
Velocity Magnitude ◽  
Model Flow ◽  
Turbulence Effects ◽  
Simplec Algorithm ◽  
Volume Method ◽  
Convective Fluxes

A series of numerical investigations was carried out to study the behavior of cavitating turbulent flows in an orifice. In the present work, two different cavitation models were used for the simulation. In the first model, flow was modeled as two interpenetrating fluids (liquid and vapor), and in the second model, the working fluid was assumed to be a mixture of three fluids (liquid, vapor and non-condensable gas). In both cases, we used a finite volume method to discretize the equations and SIMPLEC algorithm to link the pressure and velocity fields. An upwind scheme was used to model convective fluxes and other transport equations. Turbulence effects were considered using the k-ε model. Computations were performed at various inlet pressures and a fixed outlet pressure. The values of discharge coefficient obtained from the simulations were compared with published experimental data. Better agreement was found with the second model. This revealed the importance of non-condensable gases on cavitation. Furthermore, the distributions of vapor volume fraction and velocity magnitude were investigated with using both models. The results showed considerable differences between two models in description of inception of cavitation, distributions of vapor volume fraction and velocity magnitude.

Prediction of Three-Dimensional Steady Incompressible Flows Using Body-Fitted Coordinates

1993 ◽  
Vol 115 (3) ◽  
pp. 457-462 ◽  
Author(s):  
P. Tamamidis ◽  
D. N. Assanis
Keyword(s):  
Cross Section ◽  
Incompressible Flows ◽  
Three Dimensional ◽  
Computational Time ◽  
Complex Geometries ◽  
Curved Duct ◽  
Sensitivity Studies ◽  
Simplec Algorithm ◽  
Volume Method ◽  
Strong Curvature

A finite-volume method for three-dimensional, steady, incompressible flows in complex geometries is presented. The method uses generalized Body-Fitted Coordinates to accurately take into account the shape of the boundary. A collocated scheme is employed, which uses the three covariant velocities and the pressure as main variables. Continuity is coupled with the momentum equations using the SIMPLEC algorithm. It is found that the SIMPLEC algorithm can provide savings in computational time of up to 40 percent compared to calculations with SIMPLE. Sensitivity studies are also performed to find optimum values of the underrelaxation parameters. The method is validated against experimental results for the case of the flow in a 90 deg curved duct of square cross-section and comparatively strong curvature. The application of the method to the prediction of flows in complex geometries is then illustrated.

Numerical Analysis of Erosive Wear on the Guide Vanes of a Francis Turbine

2015 ◽  
Vol 741 ◽  
pp. 531-535
Author(s):  
Hong Ming Zhang ◽  
Li Xiang Zhang
Keyword(s):  
Numerical Analysis ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Erosive Wear ◽  
Francis Turbine ◽  
Two Phase ◽  
Guide Vanes ◽  
Flow Equations ◽  
Sand Erosion ◽  
Volume Method

The paper presents the numerical analysis of erosive wear on the guide vanes of a Francis turbine using CFD code. The 3-D turbulent particulate-liquid two-phase flow equations are employed in this study. The computing domain is discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The finite volume method is used to solve the governing equations and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that the volume fraction of sand at the top of the guide vanes is higher than others and the maximum of volume fraction of sand is at same location with the maximum of sand erosion rate density. The erosive wear is more serious at the top of the guide vanes.

Numerical Simulation of Nanofluid-Cooling Enhancement of Three Fins Mounted in a Horizontal Channel

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Moussa Khentoul ◽  
Rachid Bessaïh
Keyword(s):  
Volume Fraction ◽  
Numerical Study ◽  
Solid Volume Fraction ◽  
Horizontal Channel ◽  
Thermal Fields ◽  
Nusselt Numbers ◽  
Simpler Algorithm ◽  
Laminar Mixed Convection ◽  
Cooling Enhancement ◽  
Volume Method

This article presents a numerical study of two-dimensional laminar mixed convection in a horizontal channel. The upper horizontal wall of the channel is insulated. The governing equations were solved by using the finite volume method based on the simpler algorithm. Comparisons with previous results were performed and found to be in excellent agreement. The results were presented in terms of streamlines, isotherms, local and average Nusselt numbers for the Richardson number (0 ≤ Ri ≤ 10), Reynolds number (5 ≤ Re ≤ 100), solid volume fraction of nanoparticles (0 ≤ ϕ ≤ 0.10), and the type of nanofluids (Cu, Ag, Al2O3, and TiO2). The results show that the previous parameters have considerable effects on the flow and thermal fields. It was found that the heat transfer increases with increasing of Ra, Re, and ϕ.

scholarly journals Numerical Study of Periodic Magnetic Field Effect on 3D Natural Convection of MWCNT-Water/Nanofluid with Consideration of Aggregation

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 957 ◽  
Author(s):  
Lioua Kolsi ◽  
Hakan Oztop ◽  
Kaouther Ghachem ◽  
Mohammed Almeshaal ◽  
Hussein Mohammed ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Numerical Study ◽  
Three Dimensional ◽  
Magnetic Field Effect ◽  
Oscillation Period ◽  
Governing Equations ◽  
Periodic Magnetic Field ◽  
Aggregation Effect ◽  
Volume Method ◽  
The Magnetic Field

In this paper, a numerical study is performed to investigate the effect of a periodic magnetic field on three-dimensional free convection of MWCNT (Mutli-Walled Carbone Nanotubes)-water/nanofluid. Time-dependent governing equations are solved using the finite volume method under unsteady magnetic field oriented in the x-direction for various Hartmann numbers, oscillation periods, and nanoparticle volume fractions. The aggregation effect is considered in the evaluation of the MWCNT-water/nanofluid thermophysical properties. It is found that oscillation period, the magnitude of the magnetic field, and adding nanoparticles have an important effect on heat transfer, temperature field, and flow structure.

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