STUDY OF THREE DIMENSIONAL LAMINAR FORCED CONVECTION OF NANO FLUID FLOW THROUGH ECCENTRIC RECTANGULAR ANNULAR DUCT

Heat transfer through the horizontal eccentric annulus between eccentric rectangular ducts with different eccentricities has been calculated with various aspect ratio of inner duct. Boundary conditions are used with constant hot temperature on inner duct and constant cold temperature on the outer duct. Space between two ducts included TiO2-water Nano-fluid with different solid Volume fraction (φ = 0, 2, 5, 10 %). The eccentricity was changed with different values (E = 0.025, 0.05, 0.075 m) in left direction and aspect ratio was changed with different value (AR= 0.25, 0.375, 0.5). Results show that with an increase of aspect ratios, the average Nusselt number increases. Alsowith an increase in eccentricity value,the average Nusselt numberremains constant, and then an increase begins to occur. And the average Nusselt number increase due to an increase in nanoparticle concentration.

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Heatline and Massline Visualization of Hydromagnetic Double Diffusive Convective Flow of Nanofluid Within a Porous Trapezoidal Cavity

Journal of Nanofluids ◽

10.1166/jon.2021.1775 ◽

2021 ◽

Vol 10 (2) ◽

pp. 270-284

Author(s):

Bikash C. Saha ◽

T. R. Mahapatra ◽

Dulal Pal

Keyword(s):

Aspect Ratio ◽

Convective Flow ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Darcy Number ◽

Temperature Fields ◽

Computational Domain ◽

Aspect Ratios ◽

Numerical Predictions ◽

Double Diffusive

Double diffusive convective flow of nanofluid within a porous trapezoidal cavity of various aspect ratios consisting of Al2O3 nanoparticle in the presence of applied magnetic field in the direction perpendicular to the parallel top and bottom walls is analysed. The side walls of the cavity are maintained at constant temperature and concentration while its horizontal walls are insulated and impermeable. The irregular physical domain of the problem is transformed to a regular unit square computational domain. The governing equations have been solved by second order of finite difference method (FDM). Based upon numerical predictions, the effects of pertinent parameters such as Rayleigh number, Darcy number, aspect ratio, solid volume fraction and inclination angle on the flow and temperature fields and the heat transfer performance of the enclosure are examined. It is found that the intensity of heat and mass transfer increases with the increase in the Darcy number and aspect ratio. It is also observed that as the solid volume fraction increases there is increase in the average Nusselt number but reverse effect is observed on the average Sherwood number.

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Effects of a Rotating Cone on the Mixed Convection in a Double Lid-Driven 3D Porous Trapezoidal Nanofluid Filled Cavity under the Impact of Magnetic Field

Nanomaterials ◽

10.3390/nano10030449 ◽

2020 ◽

Vol 10 (3) ◽

pp. 449 ◽

Cited By ~ 6

Author(s):

Ali J. Chamkha ◽

Fatih Selimefendigil ◽

Hakan F. Oztop

Keyword(s):

Magnetic Field ◽

Heat Transfer ◽

Nusselt Number ◽

Aspect Ratio ◽

Mixed Convection ◽

Average Nusselt Number ◽

Volume Fraction ◽

Rotational Velocity ◽

Rotating Cone ◽

The Impact

Effects of a rotating cone in 3D mixed convection of CNT-water nanofluid in a double lid-driven porous trapezoidal cavity is numerically studied considering magnetic field effects. The numerical simulations are performed by using the finite element method. Impacts of Richardson number (between 0.05 and 50), angular rotational velocity of the cone (between −300 and 300), Hartmann number (between 0 and 50), Darcy number (between 10 − 4 and 5 × 10 − 2 ), aspect ratio of the cone (between 0.25 and 2.5), horizontal location of the cone (between 0.35 H and 0.65 H) and solid particle volume fraction (between 0 and 0.004) on the convective heat transfer performance was studied. It was observed that the average Nusselt number rises with higher Richardson numbers for stationary cone while the effect is reverse for when the cone is rotating in clockwise direction at the highest supped. Higher discrepancies between the average Nusselt number is obtained for 2D cylinder and 3D cylinder configuration which is 28.5% at the highest rotational speed. Even though there are very slight variations between the average Nu values for 3D cylinder and 3D cone case, there are significant variations in the local variation of the average Nusselt number. Higher enhancements in the average Nusselt number are achieved with CNT particles even though the magnetic field reduced the convection and the value is 84.3% at the highest strength of magnetic field. Increasing the permeability resulted in higher local and average heat transfer rates for the 3D porous cavity. In this study, the aspect ratio of the cone was found to be an excellent tool for heat transfer enhancement while 95% enhancements in the average Nusselt number were obtained. The horizontal location of the cone was found to have slight effects on the Nusselt number variations.

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Effects of Variable Viscosity and Thermal Conductivity of CuO-Water Nanofluid on Heat Transfer Enhancement in Natural Convection: Mathematical Model and Simulation

Journal of Heat Transfer ◽

10.1115/1.4000440 ◽

2010 ◽

Vol 132 (5) ◽

Cited By ~ 59

Author(s):

Eiyad Abu-Nada

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Nusselt Number ◽

Aspect Ratio ◽

High Aspect Ratio ◽

Average Nusselt Number ◽

Volume Fraction ◽

Variable Viscosity ◽

Cylinder Surface ◽

Transfer Enhancement

Heat transfer enhancement in horizontal annuli using variable thermal conductivity and variable viscosity of CuO-water nanofluid is investigated numerically. The base case of simulation used thermal conductivity and viscosity data that consider temperature property dependence and nanoparticle size. It was observed that for Ra≥104, the average Nusselt number was deteriorated by increasing the volume fraction of nanoparticles. However, for Ra=103, the average Nusselt number enhancement depends on aspect ratio of the annulus as well as volume fraction of nanoparticles. Also, for Ra=103, the average Nusselt number was less sensitive to volume fraction of nanoparticles at high aspect ratio and the average Nusselt number increased by increasing the volume fraction of nanoaprticles for aspect ratios ≤0.4. For Ra≥104, the Nusselt number was deteriorated everywhere around the cylinder surface especially at high aspect ratio. However, this reduction is only restricted to certain regions around the cylinder surface for Ra=103. For Ra≥104, the Maxwell–Garnett and the Chon et al. conductivity models demonstrated similar results. But, there was a deviation in the prediction at Ra=103 and this deviation becomes more significant at high volume fraction of nanoparticles. The Nguyen et al. data and the Brinkman model give completely different predictions for Ra≥104, where the difference in prediction of the Nusselt number reached 50%. However, this difference was less than 10% at Ra=103.

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Effects of circular corners and aspect-ratio on entropy generation due to natural convection of nanofluid flows in rectangular cavities

Thermal Science ◽

10.2298/tsci130201034s ◽

2015 ◽

Vol 19 (5) ◽

pp. 1621-1632 ◽

Cited By ~ 7

Author(s):

Mahmoud Salari ◽

Ali Mohammadtabar ◽

Mohammad Mohammadtabar

Keyword(s):

Natural Convection ◽

Rayleigh Number ◽

Aspect Ratio ◽

Entropy Generation ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Bejan Number ◽

Total Entropy ◽

Aspect Ratios ◽

Corner Radius

In this paper, entropy generation induced by natural convection of cu-water nanofluid in rectangular cavities with different circular corners and different aspect-ratios were numerically investigated. The governing equations were solved using a finite volume approach and the SIMPLE algorithm was used to couple the pressure and velocity fields. The results showed that the total entropy generation increased with the increase of Rayleigh number, irreversibility coefficient, aspect ratio or solid volume fraction while it decreased with the increase of the corner radius. It should be noted that the best way for minimizing entropy generation is decreasing Rayleigh number. This is the first priority for minimizing entropy generation. The other parameters such as radius, volume fraction, etc are placed on the second priority. However, Bejan number had an inverse trend compared with total entropy generation. As an exception, Bejan number and total entropy number had the same trend whenever solid volume fraction increased. Moreover, Nusselt number increased as Rayleigh number, solid volume fraction or aspect ratio increased whereas it decreases with the increase of corner radius.

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Numerical study of heat transfer enhancement in the entrance region for low-pressure gaseous laminar pipe flows using Al2O3–air nanofluid

Advances in Mechanical Engineering ◽

10.1177/1687814018784410 ◽

2018 ◽

Vol 10 (7) ◽

pp. 168781401878441 ◽

Cited By ~ 2

Author(s):

Wael Al-Kouz ◽

Rafat Al-Waked ◽

Ma’en Sari ◽

Wahib Owhaib ◽

Anas Atieh

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Aspect Ratio ◽

Knudsen Number ◽

Average Nusselt Number ◽

Volume Fraction ◽

Low Pressure ◽

Entrance Region ◽

Physical Parameters ◽

Nanoparticles Volume Fraction

The gaseous low-pressure nanofluid flow of a steady-state two-dimensional laminar forced convection heat transfer in the entrance region of pipes is numerically investigated. Such flows are of interest for many engineering applications like the nuclear reactor and electronic equipment cooling, heat exchangers, and many others. Physical parameters considered in this study are Reynolds number ( Re), Prandtl number ( Pr), nanosolid particles volume fraction [Formula: see text], Knudsen number ( Kn), and the aspect ratio ( AR). These parameters ranges are as follows: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]. The outcome of this study shows that by increasing Kn, velocity slip and temperature jump at the solid boundaries increase. In addition, heat transfer is enhanced by dispersing Al2O3 nanoparticles in the base low-pressure gaseous flow. Results show that there is no effect of the nanoparticles volume fraction with values below 0.03 on the average Nusselt number. The average Nusselt number increases [Formula: see text] as the value of the nanoparticles volume fraction exceeds 0.03. For instance, at Re = 1000, results show that when dispersing Al2O3 nanosolid particles with volume fractions of 0.3 and 0.5; there is an enhancement in the average Nusselt number of 30.35% and 136.74%, respectively, when compared to the case of dispersing Al2O3 nanosolid particles of 0.03 volume fraction.. Moreover, it is concluded that the average Nusselt number [Formula: see text] depends directly on Reynolds ( Re), Prandtl ( Pr) numbers, and the nanoparticles volume fraction [Formula: see text] and inversely on Knudsen number ( Kn) and the aspect ratio ( AR) for the investigated range of parameters considered in this study. Finally, a correlation of Nusselt number among all the investigated parameters in this study is proposed as [Formula: see text].

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Mixed Convection in a Cubical Cavity With Active Lateral Walls and Filled With Hybrid Graphene–Platinum Nanofluid

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4043758 ◽

2019 ◽

Vol 11 (4) ◽

Cited By ~ 10

Author(s):

Ahmed Kadhim Hussein ◽

Lioua Kolsi ◽

Mohammed A. Almeshaal ◽

Dong Li ◽

Hafiz Muhammad Ali ◽

...

Keyword(s):

Nusselt Number ◽

Mixed Convection ◽

Richardson Number ◽

Average Nusselt Number ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Cold Temperature ◽

Hybrid Nanofluid ◽

Cubical Cavity ◽

Lateral Walls

The mixed convection in a cubical cavity with active lateral walls and filled with a graphene–platinum hybrid nanofluid was investigated numerically and exclusively in the present paper. The lateral left and back sidewalls were kept at a hot temperature (Th), while the lateral right and front sidewalls were kept at a cold temperature (Tc). Both the top and bottom walls were assumed thermally insulated. The top wall of the cavity was considered moving with two different directions. The first one is in the x-direction (case I), while the second case is in the z-direction (case II). Also, the case of the fixed top wall was studied just for comparison. The solid volume fractions have been varied as 0 ≤ φ ≤ 0.1%, while the Richardson number is varied in the range of 0.01 ≤Ri ≤ 10. It was found that the maximum average Nusselt number corresponds to the case when the top wall moving in the negative x-direction. Also, the results indicated that the average Nusselt number increases with the increase in the Richardson number and the solid volume fraction.

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Three-Dimensional Numerical Simulation of Mixed Convective Heat Transfer in a Horizontal Rectangular Duct Utilizing Nanofluids

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1016.738 ◽

2014 ◽

Vol 1016 ◽

pp. 738-742

Author(s):

Nur Irmawati Om ◽

H.A. Mohammed

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Aspect Ratio ◽

Convective Heat Transfer ◽

Convective Heat ◽

Volume Fraction ◽

Three Dimensional ◽

Rectangular Duct ◽

Thermal Fields ◽

Nanoparticles Volume Fraction

Predictions are reported for three-dimensional laminar mixed convective heat transfer using nanofluids in a horizontal rectangular duct. Five different types of nanoparticle, Ag, Al2O3, Au, Cu and SiO2 with nanoparticles volume fractions range of 2% to 10% are investigated. In this study, the effects of nanofluids type, nanoparticles volume fraction of nanofluids and the effect of aspect ratio on the thermal fields were examined. Results reveal that the addition of nanoparticles to the base fluid and their volume fraction tend to increase the Nusselt number along the horizontal rectangular duct (i.e., increases the rate of heat transfer). It was also found that the Nusselt number increases as the aspect ratio decreases.

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Mixed convection in an eccentric annulus filled by copper nanofluid

Thermal Science ◽

10.2298/tsci140802128e ◽

2016 ◽

Vol 20 (5) ◽

pp. 1597-1608 ◽

Cited By ~ 2

Author(s):

Wael El-Maghlany ◽

Elazm Abo ◽

Ali Shahata ◽

Yehia Eldrainy

Keyword(s):

Nusselt Number ◽

Mixed Convection ◽

Richardson Number ◽

Average Nusselt Number ◽

Volume Fraction ◽

Numerical Study ◽

Solid Volume Fraction ◽

Convection Flow ◽

Numerical Work ◽

Remarkable Effect

A numerical study of mixed convection flow and heat transfer of Copper (Cu)-water nanofluid inside an eccentric horizontal annulus is presented. The inner and outer cylinders are kept at constant temperatures as Th and Tc, respectively. The inner cylinder rotates to generate the forced convection effect. The numerical work was carried out using an in-house CFD code written in FORTRAN. Different scenarios were explored to explain the effects of different parameters on the studied problem. These parameters are Richardson number, eccentricity ratio, and solid volume fraction. The range of the Richardson number Ri, solid volume fraction of the nanoparticles ?, and the eccentricity ratioe, are 0.01 ? Ri ? 100 (natural convection), 0 ? ? ? 0.05, 0 ? e ? 0.9 respectively. All results were performed with thermal Grashof number Gr, and radius ratio Rr, equaled to 104 and 2, respectively. The effects of eccentricity, nanoparticles volume fraction, and Richardson number on the average Nusselt number, streamlines and isotherms were investigated. Results were discussed, and were found to be in good agreement with previous works. It was also found that, the eccentricity has a positive remarkable effect on the average Nusselt number, while the effect of nanoparticles concentration was more pronounced at mixed convection region (Ri=1).

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The Use of Lattice Boltzmann Numerical Method for Prediction of Nanofluid Flow in a Square Enclosure

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.695.367 ◽

2014 ◽

Vol 695 ◽

pp. 367-370

Author(s):

Nor Azwadi Che Sidik ◽

Reza Masoomzadeh

Keyword(s):

Nusselt Number ◽

Lattice Boltzmann ◽

Average Nusselt Number ◽

Volume Fraction ◽

Flow Behavior ◽

Computational Results ◽

Nanofluid Flow ◽

Square Enclosure ◽

Aspect Ratios ◽

Rayleigh Numbers

In this paper, we contribute to another record of computational results by lattice Boltzmann on the flow behavior of nanofluid in a differentially heated enclosure. In the present study, numerical prediction of CuO and Al2O3 nanofluid, Rayleigh number ranges 103 - 105, aspect ratios of 0.5, 1.0 and 2.0 and nanoparticle volume fractions of 1, 3, 5 and 10% were performed. The results show that, for both nanofluids, increases the volume fraction lead to increase of the average Nusselt number for the whole range of aspect ratios and Rayleigh numbers.

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Heat transfer characteristics of nanofluids from a sinusoidal corrugated cylinder placed in a square cavity

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211027208 ◽

2021 ◽

pp. 095440622110272

Author(s):

Salaika Parvin ◽

Nepal Chandra Roy ◽

Litan Kumar Saha ◽

Sadia Siddiqa

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Rayleigh Number ◽

Aspect Ratio ◽

Average Nusselt Number ◽

Numerical Study ◽

Heat Transfer Characteristics ◽

Number Range ◽

Transfer Characteristics ◽

Wide Range

A numerical study is performed to investigate nanofluids' flow field and heat transfer characteristics between the domain bounded by a square and a wavy cylinder. The left and right walls of the cavity are at constant low temperature while its other adjacent walls are insulated. The convective phenomena take place due to the higher temperature of the inner corrugated surface. Super elliptic functions are used to transform the governing equations of the classical rectangular enclosure into a system of equations valid for concentric cylinders. The resulting equations are solved iteratively with the implicit finite difference method. Parametric results are presented in terms of streamlines, isotherms, local and average Nusselt numbers for a wide range of scaled parameters such as nanoparticles concentration, Rayleigh number, and aspect ratio. Several correlations have been deduced at the inner and outer surface of the cylinders for the average Nusselt number, which gives a good agreement when compared against the numerical results. The strength of the streamlines increases significantly due to an increase in the aspect ratio of the inner cylinder and the Rayleigh number. As the concentration of nanoparticles increases, the average Nusselt number at the internal and external cylinders becomes stronger. In addition, the average Nusselt number for the entire Rayleigh number range gets enhanced when plotted against the volume fraction of the nanofluid.

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